Begging the question; is ASIC resistance actually desirable?

It has both upsides and downsides.

The up-side is that individual miners can make a go of it with bog standard machines.
This will likely result in more individual actors mining; though it wouldn't address the issue of them coalescing into pools.

The down-side is that standard hardware is much easier to game. Botnets, or in an extreme scenario buying a ton of hardware. (Harder with ASICs; it's quite obvious what you're doing).

I think we were reasonably lucky to not be killed in the pre-GPU era. Perhaps we were just not really a target, a 'joke' at the time.

Answering the question directly; I don't see that it would be too difficult to optimize an algorithm specifically for x86 hardware; such that an ASIC would simply be x86 with a few instructions removed. The question is whether or not that's useful.