The Bladesinging subclass (Sword Coast Adventurer Guide, p. 141) of the Wizard class is restricted to Elves.

If a High-Elf with 4 levels in the Wizard (Bladesinging) class dies and is reincarnated in a Human body, then what happens?

Will they lose levels? Swap their sub-class? Keep their sub-class levels but become unable to progress any further?

I found a number of questions on how to handle racial traits after Reincarnation, but none that pertained to race-as-prerequisite for either sub-classes or feats.