Are you serious? Have you ever played a normal Bioware game? It would still be a fully voiced game, it would simply be one storyline not 8. That one storyline would have much more room to expand based on your choices. There would likely be about 10 or so companions, because they only have the one story to worry about. This was already discussed earlier in the thread.
It being an MMO adds that content like FP's, Ops, and PvP, but in exchange the story has to be thinner and more linear. To make up for the cost and to allow it to work in an MMO frame.
But you won't have chance to play different classes like BH/IA. It will still mostly be about the Jedi(maybe turn into Sith to some point).