Welcome to NF, first off.
Secondly, Foster's was not canceled. It had ended with the limit of episodes and seasons it was allowed to have. Normally shows have four seasons, but Foster's outdid those most shows twice and got an extra two seasons, but six was the final limit. This is so shows don't go on forever and get old. On one hand I'm sad it's over, but on the other I'm glad it ended the way it did - while it was still good, open-ended, nothing too drastic changed, (Cheese on the other hand...) no one died or got adopted permanently, etc. However I will not say much more because then I'd probably be spoilering it all for you.
Also, Foster's already had two movies, one was Good Wilt Hunting, and the one later on was Destination: Imagination, while Ed, Edd n' Eddy didn't have any. So I don't think there'll be anything like that, at least not anytime soon. However, because Craig and Co made a Tenth Anniversary episode of the PowerPuff Girls, there's a good chance Foster's will get that, too.
When it all comes down to it, we can only wait and see. You never know - we might get that Tenth Anniversary episode in a few years, or perhaps, something even better.