However, to believe that all processing for pro video can be done in the cloud (I'm talking about over the internet---not over a fast local network) for is to GREATLY underestimate the issues of sheer volume of footage to upload, and latency, etc.
The part that *could* work today is streaming a reasonably good-looking video preview stream of your comp window, edit window, etc.
For artists who synthetically generate all of their material from "lightweight" files like Illustrator vectors, 3D models, etc. this might not be so bad...but in the world of high quality video? Oy, the source material is, well, really big.