They could really use a third brand, which they had at the end of that run.
This will lead to a passionate Larry post, but ECW really did propel a bunch of guys and give them the forum to develop themselves on TV both character wise and in the ring. Miz, Morrison, Punk, Kofi, Ryder (two stints), Sheamus, etc etc etc.
And it wasn't just a bridge for FCW guys, because people like Mark Henry found themselves and were given a chance to shine in a larger role.
The WWE has a million B-shows. Superstars or Main Event can be the next step from NXT, which is really just the old FCW shows with WWE bells & whistles.