I can't imagine them not doing Eclipse.
I, for one, am not 100% in love with the movie, but I went three times anyway and I'm sure I'll do the same when New Moon comes out. We all love this story and want to see it on the big screen, for better or for worse.
They will keep going. And hopefully, like with HP, they will just get better and better.
"My apologies, dog." - Edward Cullen, Eclipse