It's worse than what you're stating. Spectre is remotely exploitable with network packets (NetSpectre). The current state of the world isn't just fine with process level security, and the chip vendors are going to need to fix it, because ultimately you can exploit then if you control the data, not just the code. They have several options available to them, all of which also let's you run sandboxed untrusted code in the same MMU context as trusted code.