the 10% is a pretty big sticking point. I don't know if there's an "all oldcoins moon" narrative possibility out there, but if there is, zcash is quite well primed for it. I don't see why it would have to shift away from PoW for it to happen though.
In the context of PoW coins it’s problematic - it means that there can only ever be one dev team, and they are the gatekeepers for all ZCash development. This also means that they can trivially be forced / bribed by a three-letter acronym to add “features” in. /1
Since ZCash isn’t open-source (but merely source-available) it’s naturally hostile to anonymous contributors, which - by extension - means it cannot be trusted by users who need strong privacy the most. /2