Governments in the USA spend a ton of money on roads. If they could be convinced to spend some of it on buses, I think those bus companies could make a profit.
They'd have to use some sort of marketing trickery to obfuscate the fact that they were buses, because buses carry an undeserved stigma in the USA. But I think Silicon Valley is generally pretty good at repackaging old ideas to seem new.
As private vehicles increase in size and weight, the costs of road maintenance for private vehicles will continue to increase. As fuel/electricity costs increase, private vehicle ownership will continue to get more expensive. So the rewards for implementing this would only get better.
In some places trains are better than buses. Unfortunately in the USA the costs of private car ownership are mostly borne by local governments. So I think in the short term it will mostly have to be buses.