Good point.

For what it's worth, I was imagining a gradual (say 10-year) process of introducing other mining algorithms. Like introduce CPU mining but make it so difficult, only 1 percent of blocks would be mined this way. Do the same for other mining algorithms, then gradually increase their use (decrease the difficulty). You could keep the max CPU mining to 20% (or whatever) to prevent spontaneous spin-up attacks.

Or maybe alternate blocks so each block has to be mined with a different algorithm from the prior block. Certainly would add some complexity, and possibly MEV.