SWTOR is Biowares WoW clone. However it's what a sequal to WoW would look like. It's polished and prettier but the combat system is exactly the same. I think Bioware will apply everything that works in WoW and add a couple more features that WoW doesn't have.
I'm glad some companies are realizing that trying to re-invent the MMO wheel is a mistake. Just building on what Blizzard has brought to the forefront of the genre is the way to go.
The gamebreaker in my opinion would be the difficulty of the game. If they make instanced dungeons and raiding tiered diffuctly like WoW, its gonna fail. 1 mode, like vanilla WoW is the way to go imo. Don't want to see the entire game world running around in gear that's achieved through casual play. Power to the hardcore players.