Imho, there are 3 possible problems any ACC school considering adding DI men's lacrosse must overcome:
2. Title IX considerations; and
3. Forming a competitive program.
Thing is, even if you have 1 and 2 under control, there's still 3 to deal with. Imho, if any one ACC program upgrades by itself, it will take several years before that program wins a conference game. For that reason, if you see any ACC expansion, it will likely entail two or more programs upgrading simultaneously.