I posted this in another thread, but I'll post it here, too.
I'd like for them to get rid of pets as a system, but still keep the Fairies and Egis as job mechanics.
For Arcanists, when they draw their book, a Carbuncle will appear at your heel and move with you, like it's part of your character model. Instead of Ruin and Ruin 2, your GCDs are attacks that originate from Carbuncle.
At level 30, Scholars lose access to the Carbuncle, obviously, with Eos or Selene hovering over your shoulder, again moving like it's part of your character model. The Carbuncle-themed GCDs are changed to Broil and Ruin 2 (likely changed to just Ruin, since Ruin wouldn't exist anymore in this scenario). Physick can upgrade to Embrace, making it a slightly more potent heal which features both you and your fairy casting it together. And any actions that were originally you commanding your fairy to do them would instead just come straight from you.
At level 30, Summoners keep Carbuncle, as the theme of the job should be to be using your summons and, being your first summon, it should stick around. Egis are instead summoned for powerful oGCDs, attacking like how the Reaper's Void Avatar does in the reveal trailer for it. I was thinking the Egis could be summoned from three abilities, a power single-target, a modest AoE and a support move, likely a shield. Summoners can also have access to a special menu where they can assign any Egi of a Primal they've defeated to these skills, so players are free to choose whichever summon they want for each attack. For Dreadwyrm Trance, I'd make it so that Carbuncle is dispersed with a Bahamut effigy appearing briefly, allowing us to use the form, and when Demi-Bahamut is unlocked, he's summoned along with using the Trance, to make it consistent with Firebird Trance and Demi-Phoenix.
Aside from those two, I want them to make Dark Knight more unique, instead of just "edgy Warrior". I wanted them to roll the effects of Dark Arts into Darkside and make it so that Darkside consumes Black Blood for each action you use. Since Bloodspiller and Quietus consume Black Blood, I would change it so that Bloodspiller replaces Souleater while in Darkside with a larger potency increase, and Quietus can either be a powerful oGCD, or just a GCD you can spam while in Darkside. Delirium can be changed to grant you 50 Black Blood.