Im not saying it is impossible it certainly exists in form of renderfarms (that is after all edits are done send to farm and collect back in few days). Im just saying its impractical in the edit stage. By all means if you need no feedback then its fine. But its awfully hard to get anything done in the blind.
Thing is when i use nuke or AE my biggest bottleneck is how fast i can move my data from disk to screen and back. Now im moving 500-1000 MB/s a second to the deck and its still often the slowest part now even a 1000Mb/s (note the small b versus big B bit versus byte) symmetric internert connection is 4-8 times slower than this, and has awfully lot more latency. Most likely a user gets 100 or 10 thats 40-80 to a 400 to 800 tilmes slower. And i am not a dedicated comp artist, ssd drives just are blindingly fast today.
Hardware wise getting a disk capable of moving 500 MB/s costs you about 200$ versus the network solution that does 1/8th of that speed costs you 200$ per month, if at all available in your locale. God forbid your operator having any transfer caps and you would chew your bandwidth allocation in day.
So in terms of costits cheaper to find a comp software that works on your local machine than buy it as SAAS, today, but it might change. SO what im saying is with current tech it cheaper to buy the hardware yourself. Software you can get for free if you can put up with opensource.
The situation is much better for offline final rendering where the data has to be pushed trough the pipes only once.
Revolutionary or not its still a good idea to do it locally the operator is still more expensive than your savings. So i dont see SAAS as practical at current tech levels. On the oethrhand you can get nearly saas by renting your comp software by the week or month for your local machine. This is allready available.
For example you can rent After effects with 24$ month, for your local machine, pair that with 100-200$ for a new disk your home free. For most simple stuff thats way enough for modern computers. Im not seeing saas getting anything cheaper here.