Even the MMO system they used would be a poor fit for a modern single player crpg.
It's not Bioware remaking the game, so no danger of that. The developer remaking it is Aspyr, which up until now, primarily ported games to new systems, including both KOTOR games. On the down side, this is their first major game, so it's hard to tell where to put expectations, quality-wise. On the up side, I'm frankly
more confident in the prospects of the game than if it
had been Bioware, given their recent output.
As for combat, I agree, the d20 system in the original hasn't aged so gracefully that it could make the cut for a remake (remaster, maybe). Unless WotC is willing to license them to use Saga Edition, I can't really see them using d20 at all unless they want to go the Solastra route and just OGL the whole thing. More likely they'll either try to make an original system (which anyone's guess on how well they'd manage that) or even
more likely, they'll try some kind of action RPG system.
Of course one outlier would be if Lucas Arts arranged for them to use the FFG Star Wars RPG system, which would be
interesting. Not sure how well that would translate to a digital format.