Meltdown: affects only Intel CPUs, is the 'biggy' short-term, but patches to mitigate it are landing as we speak and patches to eliminate it using trampolines are described in the paper. So no need to replace your Intel CPUs unless you can't live with the performance drop, but a good reason for buying AMD going forward.

Spectre: hits AMD too. Hits everyone today. Hope for a new arch (bias: I am a Mill CPU dev ;) )