So, I am left wondering why this requirement is listed for the killer alt coin in the OP;
"provably cpu-only mining"
It seems to me that now that SHA 256 ASICs exit that are much less electricity hungry, that they would get pointed to the alt coin as BTC becomes too hard to mine. That hardware can ONLY mine coins. As BTC gets too difficult, owners of older ASICs will simply point them at other SHA 256 coins. That is my theory. Am I missing something?