I think doing any consensus algorithm change, no matter how trivial, would disrupt, endanger, and delay the Overwinter and Sapling projects. And, changing the PoW isn’t that trivial. (Although it is a lot easier than a major novel innovation like Sapling!)
The Zcash Foundation just announced that they are funding research and engineering resources immediately, so maybe we can learn exactly what it would take to change the PoW, etc. from their efforts.