I'd say I prefer this SMN over ShB SMN, but that comes with a caveat. As I mentioned, I like the direction of this SMN, but not the execution, and I think what makes me like this iteration more than the last is that I have more hope for its potential and too much distain for how disconnected Aetherflow and Egis were from the actual act of summoning from ShB, but that's also not a very fair take--to like something for what it might be vs what it actively was.
This SMN is an incomplete puzzle, and a part of that may very well have been intentional. There is a lot of room to build on this SMN over the next 10 years without running into another design ceiling. The garden was overgrown, and the solution was the gut it, then replant only half the garden. On some level, it makes sense, but they could've left the DoTs and old Tri-Disaster, and with a little tweaking to the current arrangement, it may have felt more complete, even if still inflexible with the summons as they are right now. Because even if they don't fit into the future picture, you can always remove them when you're ready to replace them with something more in line with the job's new direction. That's how I foresee Aetherflow going.
I have a few ideas for things that we might see in the coming expansions. Something others have brought up is having Ramuh, Leviathan, and Shiva replace Ifrit, Titan, and Garuda for one use each after summoning Bahamut or Phoenix perhaps, so you'd have a rotation of say Baha > Levi > Ramuh > Shiva > Phoenix > Titan > Ifrit > Garuda > Repeat, or something. Frankly, I cannot imagine R/L/S existing independently of I/T/G as six different variations of DPS just does not fit within the the rules of how this game works. Having a 4th summon of some kind I can see where there's one additional choice of flexibility, but not three. Maybe not exactly as I've written it, but something along those lines seems like the most realistic way to ever get the other 3.
Beyond that I could also see Alexander being a separate action that can be substituted for Bahamut or Phoenix on a 3 minute cooldown or so for a hyper DPS phase where you get to summon Bismarck and Ravana as two longer summon phases in lead up to your next Bahamut/Phoenix, though that seems like more of an 8.0 thing if at all.