It can work, of course. However, it would need the right cast and crew, but it's going to be tough to watch a Batman A) other than Bale and B) not written and directed by Nolan. Will it be better than the Avengers? Probably not, that would depend on the villain. All the characters, outside of Batman and *maybe* Hal Jordan GL, are perfect characters, and always have been. They've got no flaws.
It's going to be hard for the movie to be good (because it will make as much money as Avengers 2, regardless if it is good or not) considering you'd have to rush the origins of The Flash, Martian Manhunter, Green Lantern (if they go with Stewart, Rayner or Gardner), Wonder Woman, Aquaman, or whoever else is on the team. And like I've already said, it is possible, but it would need the right cast and crew. Another problem is this: would we be getting old versions of the characters, or revamped New 52 versions of the characters?
I'd be lying if I said I wasn't interested, because I am, but I can also say that I am far more interested in Antman and Avengers 2 for 2015.