Disclaimer: not a language designer/implementer (yet). Couldn't segmented stacks for async/await-style IO be simulated by swapping the stack out at every await

Disclaimer: not a language designer/implementer (yet). Couldn't segmented stacks for async/await-style IO be simulated by swapping the stack out at every await? I mean copying out the registers and the raw stack to some heap location, then restoring them by reversing the process later. (One problem I see is that it'd be slow when lots of IO operations are involved.)