While I think it is entirely possible some/many communities will opt to extend the school year through distance learning, there are a number of reasons why it might not happen in many places.
It isn't just tradition stopping schools from suddenly running year round. Just like Disney, there are laws and contracts to negotiate. There are local laws, state laws, and federal laws.
Running schools into the summer would mean different things in different locations. Some school systems already operate on a year round schedule, other locations might have air conditioning, nor the $ to run AC.
Many states also rely on say, summer tourism or summer farming, in those places the local business interests might lobby hard to have state resident families out of school come summer.
Again, I'm not saying it can't be done. It just might not happen in a number of places for a wide array of reasons.