Tesla are making a 300 mile one and a 500 mile one. First deliveries to Frito Lay are in December. They’re also setting up a Megacharger network. Drive 4-8 hours, park for an hour, then a second leg. It’s becoming viable.

Edit: for accuracy, it looks like Tesla are not doing an entire megacharger network but rather installing them at client locations. In light of that, these trucks may remain more for regional hauling than cross-country. But if someone were to put chargers at truck stops, they’d work for both.