It used to be usual to buy a new Lego kit for each robot built, each season.
Schools may have Lego kits, but there’s not a lot of stuff that would be carried over from season to season.(1)
I think the roughest part of the transition will be the software, but that has always been a relatively small part of the whole FLL “game”.
(1) Massive exception for schools that are all-in on a Lego+FLL program, but I think that is a tiny minority.
The robot kit can be kept and used again each season. Only the challenge kit (mat and mission models) change each season. The current robot kit is $540 vs just $95 for the challenge kit.