Intel have cleverly conflated Meltdown (the really serious Intel bug) with spectre (the pervasive but hard to exploit vulnerability) even putting the serious one last calling it “variant 3”, the industry have bitten and the Intel’s view of the world is becoming fact!
Of course kernel vendors will only want one version of a kernel, so if they patch this generically - all CPUs will take the hit. Shameful really because they’ll be slowing AMD CPUs when there’s no need. If there’s any justice in the world after the initial panic, code will be refined to allow the kernel to run in it’s old non-isolated state on AMD machines.
For the spectre attacks on cookies turn first party isolation on in your browser - for firefox do this: