Obviously MP will finish the tour with Zakky and the boys....
And then what?
Being the mercenary drummer might be cool for a while, but I see him writhing in pain not being in DT after they move forward. I guess we will have to wait and see, but other than joining some novelty super-group or sticking with A7X, what else do you see him doing?
If A7X asks him to be their drummer, permanently, it will signal that they are also ok with him being not just a drummer, but a driving force in the band. If that happens, I expect him to accept.
Then, nothing changes with MP. He'll do his side projects, with A7X replacing Dream Theater as his "big band."
That said, if A7X doesn't want MP to artistically contribute in a heavy way, I doubt MP would accept the gig. MP needs to be in control It is in his personality. He can say what he wants and he obviously can be a session guy here and there, but for him to be happy, MP needs to have his hands in the middle of whatever he's doing. That's just his nature.
So, if the A7X thing doesn't pan out, I see him doing a few side projects for a couple of years, and then him doing what he hinted about and trying to rejoin DT after the next album and tour cycle is completed.
Honestly though, I see A7X wanting him in the band full time, and contributing. A7X, love them or hate them, isn't your typical metal band. They really go in different directions, and it is actually progressive in the vein that they experiment a ton. If MP was allowed to help drive the ship equally, that's a gig I see him taking and using that as his replacement for Dream Theater.