Optimistic of you to assume that future operating systems will run on local compute. Windows 35 requires datacenter level resources, but cortana will sell you minecraft capes with real-time emotionally personalized unskippable advertisements!
That's the whole point of an operating system - to manage local hardware. That's its reason for existing. The moment task switching starts depending on rtt to a cloud provider's servers, it's just a thin client with delusions of grandeur. Fifty milliseconds per system call, and no amount of tflops on the backend is going to save you from that feeling of working through a proxy in 2005