ECF is not a gimmick. It really works for me (I've got an EOS 5).
My guess is that Canon is reserving some tricks in its sleeve. Think about it, how many more revolutionary developments can happen? (Megapixels alone won't help push people to buy new cameras) Let's count the ways....
1. Live LCD preview
2. Film-like dynamic range.
and then somewhere, I think they'll spring a surprise return of....
3. Eye controlled focus.