It affects them buying players, and up front will be a struggle for them next season.
Hazard wants out, and Higuain is on loan. That leaves them with very few options. They've had to give Hudson-Odoi match time this season, which shows what kind of state their forward line is in. If the ban stays in effect, I'd expect Tammy to be on the bench and getting regular minutes next season.
The ban was nothing to do with finance, it was to do with their signings of foreign youth players. They don't need to sell, and why would they if they can't buy?