I'm not really convinced we need to continually update the instruction set with non-scalable vector instructions either tbh, it seems like we've stalled on 256

I'm not really convinced we need to continually update the instruction set with non-scalable vector instructions either tbh, it seems like we've stalled on 256 bit wide instructions to the point where AMD is emulating 512 bit instructions using 256 bit wide execution units and the performance benefits of 512 bit wide instructions even on Intel is marginal at best. That's not to say scalable instructions are a bad idea. It certainly makes it easier to make small CPUs which support all the software written for vector instructions without having to emulate 256 or 512 bit wide execution units.