The problem with reinstating Aegis is that one of its former leaders is in prison, most of its former pilots and military assets were probably lost on Tuesday, and all three superpower leaderships are in an extremely politically precarious position right now having backed Salvation so strongly. The Baumann report also wasn't wrong about a lot of the failings of Aegis - which are perhaps intrinsic to that sort of inter-superpower co-operation.
There's perhaps room for voices like Winters or Kaine to demand it, but to actually have it happen would need them to be able to go from the current situation to actually being in charge. Routes for that in each superpower and power:
- Federation: vote of no confidence in Hudson is possible and would probably succeed, but no guarantee that it would be Winters rather than Archer getting made President afterwards, since the Republicans still hold the balance of power in Congress and Archer's domestic focus has meant he hasn't really got any of this crisis on him. Hudson might be persuaded to resign in favour of Archer to avoid a VoNC, perhaps?
- Empire: obviously ALD is the absolute dictator and that isn't going to change (and was sensible enough to slightly hedge her support for Salvation's plan, too). With Tesreau, Aisling Duval and Hadrian Duval all opposed to working with Salvation in advance - and Tesreau, at least, ALD seems to respect personally - I expect she'd be happy to look for alternative routes. That said, Hadrian Duval can say "this is what happens when we work with the other superpowers" and argue for isolationism just as much as Tesreau can argue for that sort of co-operation in terms of Aegis.
- Alliance: the Assembly can of course get rid of Mahon in favour of Kaine (or perhaps Corcoran) at any time, though Mahon of course was pro-Aegis anyway. He's likely to try a "with Salvation dead, Sirius is the only partner offering us support against the Thargoids" approach to reinforce his position, I think, and wouldn't oppose bringing Aegis back if anyone else was interested.
- Sirius: they get to bill the Alliance for the significant loss of personnel and materiel and of course would welcome Aegis returning and needing lots of kit selling to it at emergency prices. Their worry is Mahon being replaced by Kaine (who hates them) or Corcoran (who'd likely sooner be rid of them) so expect some action from them to try to stabilise his position.
- Utopia: not really militaristic in the same way as the other powers. Antal opposed Salvation but never really backed Aegis either. Did suggest the peace conference between the superpowers initially, of course, so might make a reasonable neutral-ish broker to try to set things up again.
- Grom: opposed Salvation, but is never going to trust the Federation enough to work with them on any sort of joint project either.
- Delaine: the one Salvation-supporting leader who is unlikely to face any consequences for it, because his group likely still agrees that wiping out the Thargoids is a good idea and it's just that Salvation went about it the wrong way, because he probably didn't take any actual losses when it went wrong, and because he's already successfully fought off a coup attempt recently and it'll be years before anyone can get the organisation together for another.
- Colonia: not a militarily significant power, and its xenological research is mainly not Thargoid or Guardian related. Likely holding emergency Council meetings right now to ensure that supplies and accommodation are prepared for a substantial wave of refugees in the event that the Thargoids press the attack.
All in all, I do not expect any significant inter-power co-operation in what comes next...