YES! If P != NP then there is an infinity hierarchy of problems between them which are themselves complete in terms of difficulty within their level.

https://en.wikipedia.org/wiki/NP-intermediate

Under the assumption that we understand P and NP a heck of a lot more if we were able to proof their distinctness, this hierarchy could possibly be used for actually USEFUL proof of work in crypto currencies, by choosing problems with exactly the right difficulty from a problem domain like protein folding.