> Would you say GPU compute was envisioned in the 80's?
Well, GPUs aren't used for general computation either. There are specific sets of problems that they're good at, but we don't run the OS on them.
Xeon Phi's predecessor, the Larrabee, was designed as a GPU. Intel now has a Phi that can be the only CPU in your computer.
It all depends on the code that the GPU cores run.
Some time ago, while musing about what a modern-day Amiga would be, I'd imagined it'd have a GPU and run all (or, at least most of) its software on it.