Nvidia optimus or their laptop setup for swaping gpus, it doesnt turn off the gpu, at least to what i have tested
That may very well be. Powering off the graphics card is likely 100% an Operating System issue, i.e. Windows doesn't take to kindly to PCIe devices just disappearing and reappearing. So enabling some kind of sleep state on the GPU would be the simplest workaround.
That's why Apple has been ahead of the curve in that regard. They spec'ed the behavior to nVidia and AMD and provided them an easy API to latch onto. Microsoft, not being in the laptop business (before Surface), has probably not seen the necessity.
How is Linux support?
If you google "nvidia optimus linux" it does come up with lots of results. I have absolutely no experience with Linux, so that's as far as I go.
hell, do we even need a CPU if the GPU becomes the controller?
Technically, both are microprocessors. Both are Turing complete, so in theory interchangable.
It's just that GPUs have a very different architecture. A desktop CPU has between 2 and 8 cores, each capable of doing highly complex calculations. A GPU has up to 3000 "cores" (stream processors, Unified Shader Model), each dead simple and only good for simple calculations.
Thus, a GPU is only effective if the problem it's computing can be broken up into many many simple calculations. If it can't, it falls apart. And if the last 9 years of multi-core CPUs on the desktop have taught us anything, it's that a lot of software problems cannot be easily multi-threaded.