The only thing that interests me about this is the character kit implementation. It's a thing that could actually significantly improve both first BG and first IWD as boring character progression is the main flaw of these games. Of course this should be done with careful rebalancing, otherwise some kits known from BG2 would be ridiculously over or underpowered. So, judging by the quality of the stuff that can be seen on screens and read in the interviews, I'm not holding my breath.
I can't think of any kit or class from BG2 that would be overpowered in BG1.
One spirit animal summoned by totemic druid would probably be able to beat Sarevok one on one and would cut through 3/4 of the game like blade through grass.
Shapeshifter druid would be hugely op. Berserker would be hugely op. Undead hunter and Inquisitor would be op. Assasin's poison and the traps from that other rogue kit would be op as well, though that would be mostly dependant on player's willingness to cheese.
Edit: Yes, Bard kits as well - the one that can confuse all enemies through a song and the one with skills giving crazy combat bonuses.
Also, Inquisitor is way op in general so perhaps this shouldn't be blamed on porting it 1:1 to BG, but still.