>Are we going to have to design our crypto algorithms entirely on SIMD instructions to combat this sort of thing?

There is likely still potential for side channel attacks. From a 'first principles' approach a computer is always going to leak information about it's current state (power, noise, emi, etc) and the methods / tools / techniques for analyzing that leaking information are only getting better.

The multi-tenant nature of modern infrastructure is the bigger issue in play here.