Widebodies would not be economical if flown empty, most especially on short domestic routes. Domestic pax expect frequency, so you can't replace multiple daily departures with one flight every day or two.

Also there aren't enough widebody gates for all those turns, and most of those are in international terminals.

It could be done if there were some kind of national crisis in air transport capacity, but nobody who has to turn a profit will likely go there. Maybe a very few transcons or maybe shorter NAT routes?