Things I've 100% noticed from the new SMN (with a bit of speculation too).

[Gallus]

1 - Demi Bahamut seems to no longer cast wyrmwave on OGCDs, notice how he does his usual wyrmwave when the SMN casts ruins but he doesn't do anything when the SMN casts tri-disaster. This obviously simplifies things, as you don't need to save your OGCDs or time them up with your Bahamut phase to make optimal damage. Also, no more Virus for that extra wyrmwave. I actually sort of like that.

2 - Pretty sure the skill aetherflow is entirely gone on the SMN. Painflare and fester still cost 1 stack, but now Energy Drain is your new aetherflow. Notice how in the video the SMN casts Energy Drain and they get their 2 stacks back.
I suspect Energy Drain will have a CD now.

3 - As for phoenix itself, there's something very weird going on in there. Unlike with Bahamut, the SMN himself doesn't seem to cast anything but rather command Phoenix to do stuff instead. The first thing casted seems to be your spammable exclusive Phoenix ruin (which seems to be an instant cast), the second thing casted seems to be a more potent spell (likely to have a short CD allowing 2 or 3 of these ones during your phoenix phases, no idea if it's gonna be a CD or OGCD though), the third one is the equivalent of Bahamut's Akh Morn, likely to be OGCD and be able to be casted once or at best twice during your entire Phoenix Phase. So we might have an entire different set of buttons for the Phoenix transition (likely no more than 3 or 4 though). However, this is speculation.

4 - Dreadwyrm Trance? Shadow Flare? Aetherpact? Deathflare? Enkindle? Sustain? Rouse? Pretty sure all these are gone.

5 - Your rotation seems to consist on going between Phoenix and Bahamut back and forth.

6 - This is just speculation, but from what I've seen, the Phoenix + Bahamut uptime could be almost 100%. Why do I draw this conclusion? Because pet actions have been eliminated, now Garuda and Ifrit only have one action, so having them there just plain autoattacking doesn't sound very exciting, and if my predictions are correct and rouse is gone too this further proves I might be right about this, since now, there's no reason to wait to hold on Bahamut/Phoenix because of your Roused Egi. So perhaps you may want to have Garuda/Ifrit for a few seconds out to cast their one and only action now, and then swap them for Bahamut/Phoenix. This is speculation though.

7 - I noticed one new spell too in the Bahamut Phase. Could very well be a Ruin V. It seems to be hardcasted (and it seems to be a relatively long cast). (I could be totally wrong here and as another posted mentioned, it could very well be tribind, my apologies).

8 - I predict now Bahamut and Phoenix cost being either 2 stacks of aetherflow or 4, depending on Energy's drain new CD. The 2 feathers on the Phoenix icon lead me to think that. Each feather either costs 1 or 2 stacks. I'm more inclined to think each feather costs one stack. Speculation again though.

9 - Both Summon Phoenix and Summon Bahamut might be locked behind a 25-30 sec CD, to prevent spamming one.

10 - As for Titan-Egi. I predict it'll become your defensive pet. It won't transition into a greater primal but it might give the SMN a more defensive approach where Titan-Egi keeps debuffing the target he's attacking so that it does a bit less damage or Titan Egi's action casting an AOE defensive buff on your partners. Titan Egi's new action is called Earthen Armor so everything seems to be pointing this way. This of course will come at the price of doing less damage.

[XenabelleS]

Sustain is definitely gone as pets won't take damage.

I am super concerned what that means for Titan though. I reason I main a summoner is that I don't like the mobs to be standing in my face, hitting me without an effective heal.

[Iscah]

The 50-60 SMN quests had quite a lead-up to learning Dreadwyrm Trance, so I don't know what they're going to do with that questline.

Also, Phoenix. To summon an egi we need to defeat the primal. To defeat Phoenix (unless we encounter it on the First) we need to clear the Binding Coil.

Are they going to write around that or make a break from their usual "sidequests didn't happen until you do them" approach and assume it already happened?

[Zeich]

Gallus - From your list, the only thing I have to point out is from #6 - I don't believe Ifrit and Garuda only have one action. During the LL, they showed how they were crunching together Egi abilities, and with the example, they showed one ability from each Egi combined into a single ability called "Egi Assault 1." This leads me to believe it's only the first one, and that we'll likely have multiple Egi Assault abilities.

Iscah - I'm mixed on this; I don't remember "beating" Bahamut as part of learning his Egi. Instead, if I'm remembering the quest correctly, we went to the site of Cartenau and learned to draw from the aether there to Trance for the first step. We didn't fight Bahamut when we learned Summon Demi-Bahamut either; we instead fought the Sari-Egi and the Evocation Matrix. We could be pulling something similar with Phoenix - being an egi related to fire/light/life, it could be that our trip to the First helps us attune to a similar type of aether in order to learn how to summon Phoenix.

[Maneesha]

about 4: i wouldn't be so sure, its possible, but saying you are sure is early. bahamut summon was already ready on the start of the vid, so we don't know if we have to go trough 2 or maybe just 1 trance to ready our bahamut.
about 1: he decidet to cast a skill, after it hit bahamut did move, like he usually does when he performs wyrmwave.we all know that while we cast bahamut isnt doing anything but looking good, until our spell hits and he performs wyrmwave then, so we might still be spamming oGCD's during bahamut/phoenix.

Edith: there is one instance where bahamut didnt cast on oGCD, this is when the summoner applied tri-disaster, maybe they changed the conditions how wyrmwave activates? maybe it activates now every 3 or 5 sec and is not tied to us using skills anymore?

[Daralii]

Gallus - From your list, the only thing I have to point out is from #6 - I don't believe Ifrit and Garuda only have one action. During the LL, they showed how they were crunching together Egi abilities, and with the example, they showed one ability from each Egi combined into a single ability called "Egi Assault 1." This leads me to believe it's only the first one, and that we'll likely have multiple Egi Assault abilities.

Iscah - I'm mixed on this; I don't remember "beating" Bahamut as part of learning his Egi. Instead, if I'm remembering the quest correctly, we went to the site of Cartenau and learned to draw from the aether there to Trance for the first step. We didn't fight Bahamut when we learned Summon Demi-Bahamut either; we instead fought the Sari-Egi and the Evocation Matrix. We could be pulling something similar with Phoenix - being an egi related to fire/light/life, it could be that our trip to the First helps us attune to a similar type of aether in order to learn how to summon Phoenix.

It's a matter of being exposed to a primal's aether, not necessarily defeating them. Carteneau is drowning in Bahamut's, and considering it was also where Phoenix was born, the same could easily apply to him.

[Caduagm]

4 - Dreadwyrm Trance? Shadow Flare? Aetherpact? Deathflare? Enkindle? Sustain? Rouse? Pretty sure all these are gone.

7 - I noticed one new spell too in the Bahamut Phase. Could very well be a Ruin V. It seems to be hardcasted (and it seems to be a relatively long cast).

Well, actually, you can see through the benchmark trailer a kind of "Phoenix Trance", so I would go and say that, probably, Dreadwyrm is not gone. Maybe the traces will channel the next demi-primal you're gonna be able to summon.
Also, shadowflare has been seen through a picture of a 5.0 FATE boss.

Abou the Ruin V question during bahamut: I'm pretty sure that was just a Tri-Bind hardcast.

[Iscah]

True, we didn't actually (definitely) defeat Bahamut, did we?

But still, the quest revolves around his specific aether - our previous exposure to it at the Calamity (hand waved for non-legacy characters) and then visiting Carteneau to further draw on his power and learn to summon it.

I think I'll have to replay those quests on my alt before they get erased/reshuffled.

[Miminming]

Will bahamut follow you and not attacking if you move?

[Fyce]

Because pet actions have been eliminated, now Garuda and Ifrit only have one action [...]

Pet actions are not gone. You just don't have a direct access to them anymore. You will just press Egi Assault in order to activate a skill from your current pet.
On this slide, you can see that Crimson Cyclone (revamped?), Earthen Armor (revamped and name change?), and Aerial Slash will be activated when you press Egi Assault I depending on what pet you have out at that time. This strongly suggest that there is at least Egi Assault II which would activate other pet skills. Galvanize will probably stay too.