I'm not trying to flame you in ANY way, but why the hell would they want to do that?
Mass Effect was a great game, sure, but that doen't meant Obsidian can't do their own greatness. And I HATED Mass Effect on my PC. Seems to me that Mass Effect was exclusively desingned with console gamers in mind.
Better off doing something different for K3, if you ask me.
Yeah, ME was designed for the 360 because, well, it was developed for the 360. Anyway, if Obsidian wants to copy ME's combat system, there are much better systems to copy. ME's greatness wasn't in combat. Pick GoW, or something.