My two cents on the line-up.

While I'd love Bonehead, Gem was in the band longer, and has pedigree in both Beady Eye and High Flying Birds so I can't imagine he won't be there, especially given he regularly switches to lead too.

Similarly, while he joined Oasis much later, Chris Sharrock was in BE and HFB.

The key point being that both Gem and Chris have maintained a working relationship with both brothers over the past fifteen years.

Mike Rowe is bound to be there on keys, given he was an Oasis stalwart and remains part of HFB.

Bass is the only tricky one. There's no chance of Guigsy, and Noel/Andy don't seem like best buddies. My money would be on Jay Mehler. Played bass for latter-day Beady Eye, and guitar for Liam since 2017. Although Jeff Wootton has also done bass duties for both brothers in the past, so could be another (albeit less likely) option.

So,

OFFICIAL BAND:
Lead Vocals - Liam Gallagher
Lead/Backing Vocals, Lead/Rhythm Guitar - Noel Gallagher
Rhythm/Lead Guitar - Gem Archer
Drums - Chris Sharrock

TOURING/LIVE MEMBERS:
Bass Guitar - Jay Mehler / Jeff Wootton
Keyboards - Mike Rowe

That's essentially picking up where they left off, but with a new bassist that has form with Liam over the last ten years.