[mhh__]

AVX-512 is not going to be discontinued. Intel's reticence/struggling with having it on desktop is irritating but it's here to stay on servers for a long time.

Writing code for a specific SIMD instruction set is non-trivial, but most code will get some benefit by being compiled for the right ISA. You don't get the really fancy instructions because the pattern matching in the compiler isn't very intelligent but quite a lot of stuff is going to benefit by magic.

Even without cutting people without some AVX off, you can have a fast/slow path fairly easily.