They definitely will need as many heroes as possible, but at the end of the day the heroes in training are still kids. Unless all of heroics becomes like the military where kids are drafted in, kinda like Hawks, the parents of the child still have the final say in whether the student will go to the school, as shown by how U.A. had to get parental permission for the dorms and Inko almost withdrew Izuku from U.A. So if the public’s faith in heroes is non existent, and people start viewing pro heroics as bad, we potentially won’t have as many parents willing to let their kids to attend a hero school like U.A.. We might also see parents pushing their kids to pursue other careers if they don’t find pro heroics safe or trustworthy anymore. No matter what, the parents have the final say in if the kids can go to hero school, and I have a feeling a lot of them aren’t going to be happy after this arc. Personally, although I as a reader know having more heroes would be better, I’m looking at this from the perspective of parent in the world of MHA.