What will happen with unused 120 boosts in Shadowlands?

Since the leveling system is getting reworked in Shadowlands, I was wondering if I would be able to keep my 120/60 lvl boost. Or will it disapear? Hopefully I didnt waste the extra $20 on the preorder.

Unused boosts don’t disappear, and like previous expansions, they should adjust to the new level cap.