I don't think we'll see Wrex be a team member again. He may appear in some cool scene leading a united krogan force against the Reapers in some way or another, but crew member... nah. I think Tali should go back to Migrant fleet, she hinted at people wanting to become an admiral which would help to possibly get the Migrant fleet's support against Reapers. Jacob and Miranda will probably still be there, Garrus should be too. Thane is dying, so I'm not sure if they'll have him there. Grunt should be there too, no reason not to be unless he goes back to Tuchanka, but then you'd need a krogan teammate so I think he'll still be there. Then you have Jack, who I also think will leave and go universe trotting about without care or concern for you or the Reapers and Samara who will likely go back to being a Justicar. I haven't played with Zaeed or Kasumi, but guessing Zaeed won't be around since the job is over. That leaves Legion, who I could see being gone most of the game trying to form consensus among the geth in order to fight the Reapers and possibly heal old wounds between the geth and quarians. As for Ashley, I doubt she comes back and Liara maybe... actually I could see Liara being in the team again.