I think the ACC leftovers would be beyond stupid if they don't want to expand now. However, they are tied to the dumb long-term contract they signed with ESPN, and there isn't an automatic clause to pay the new team(s) more money pro rata so that will have to be negotiated with ESPN.
The question isn't if the ACC would like to expand or not, the real question is if ESPN is interested in paying some money to get some extra inventory. I am not sure what is the worth of UCONN, but our men's and women's basketball content got to be worth something.