Both and neither. Hybrid drives will win the war.
Slow mechanical drives paired with small like amounts of super fast flash memory, and possibly a larger amount of slow flash memory, where the flash mirrors commonly accessed data.
SSD’s will like remain a niche or business product, until bulky PCs go the way of the dodo, replaced by tablets, wearable pcs, mobile phones, smart walls/tables/surfaces & etc, in which case, localized storage will go the way of the dodo, and everything will be clouded.
Large data farms will continue, or evolve, to use ssd’s for recent/common material, and hdd’s for bulk/off-line storage.