After you have reached the highest rank in PVP and there is no more PVP armor to unlock, you can start earning more points toward the ability to unlock more and more PVE sets.
But you still have to have earned those sets in PVE. Through PVP, you can unlock the ability to wear more and more PVE sets in PVP.
Maybe earn a token to apply to a PVE item to be able to wear it in PVP
I think