Wait a minute, they're going to be totally gone? Is that right? I though Mission Control was in addition to Exposé and Spaces?
Better to say that Exposé and Spaces morphed into Mission Control. But Spaces lost a lot of functionality in the transformation. Spaces are more dynamic, as they can be created and deleted as needed and are not fitted into a rectangular grid. The new Full Screen App feature puts full screen apps each into a space. Sounds good, but at least with my trying it out (especially on a dual display system) it has been sorely lacking.