Frost is moving from Unacceptably low to bottom mid tier
Unholy is top mid tier
so they are both squarely in the "mid tier" bracket exactly where DPS should want to be, though Unholy has a better suited toolkit for every EN and NH fight you should be able to play effectively either spec and not feel ostracized.
also remember the top outliers are receiving larger nerfs than frost is receiving buffs bringing the whole DPS spectrum closer together.
this all happens 36 hours after i spent my banked 52k AP "Hakuna Matata" guess more Mythic+ spam