If they hold on to their existing vehicle than thats just another upside. If they buy a new gasoline car instead of an EV this is bad. But EVs dont have to be insanely heavy if we stop the whole cars getting bigger and bigger and bigger and bigger crap. They will still be heavier than their gasoline counterpart but one solution might be 2 tax brackets: One for gasoline cars and one for evs that has the same taxation levels but allows for, lets say, 500kg more weight in them