This is terrible news. Mythic is a mediocre developer at best and they dropped the ball on Warhammer:Age of Reckoning. Also, their only other (finished) project was Dark Age of Camelot, so they have a grand total of two games under their belt (Imperator doesn't count since they didn't finish it). On the other hand, Bioware is a tried and true RPG developer with a consistent track record for making good games.
This can mean a few things. First, EA is going to bully Bioware into focusing on MMOs which would be tragic to say the least. I'm optimistic about SW:TOR, but I'm even more enthusiastic about Bioware's single player games. It would be a crying shame to see one of the last vestiges of western RPGs go down the drain and leave the genre.
Second, Bioware will get the "benefit" of Mythic's experience and I don't see that as a good thing. They managed to screw up WAR and then managed NOT to fix it. And they did so while using the outdated and overused staples of the genre as passed down from the days of EQ. The only reason why I'm interested in SW:TOR is because it sounded like Bioware was trying some new concepts there, but with the addition of the Mythic team I fear that this means the game might get shoehorned into a more conservative EQ/WoW ripoff.
Third, I don't see any benefit for Bioware from this for their non-MMO projects since Mythic hasn't had any experience with a non-MMO game. They're just getting a bunch of guys with dubious skills to water down their talent pool. WAR had fairly bad graphics, I didn't notice any particularly good writing and the bugs were plentiful.
Overall, if this is a full scale merger, I fear for the quality of future Bioware games. If Mythic is only being brought in to help with SW:TOR, I fear for SW:TOR and what little promise that game had. A dickmove by EA, to say the least.