Ok, so I know this is going to be controversial, but:
ToB was a disaster. Gameplay-wise it is so bad as to be unplayable, 2nd edition and infinity just doesn't work at this level, and HLA's just compound this - without exception they are all awful.
Even if you don't dislike the ToB gameplay as strongly as this, I think most people will tell you ToB was by far the weakest part of the BG series.
Putting gameplay aside however (perhaps it is fair to say "Well if you don't like it then just don't play it)
The writing was EVEN WORSE than the gameplay. It is an unbelievable, disappointing setting with DBZ type powerlevels, and poorly written NPC's and dialogue.
Sarevok should never ever have happened - it was just lazy and unjustifiable, and ultimately it was an incredibly disappointing ending to and otherwise great series of games.
So, what I would like to see is the complete retconning of the whole of ToB in BG2:EE and rebuilding high level gameplay and the ending to the Baldur's gate series from scratch by the new team.
Maybe this is impossible becuase of contract limitations, but then please at lease write an "alternative" (more correct) ending after all these years.