You're right but the problem is subsidies change that math. If the US gov subsidizes oil, then the economics of that work out even if solar wins in a free market.

That's true, but also requires that companies believe those subsidies will remain in place over ~20-30 years. Assuming US elections remain fair, that's not going to be the case. By contrast solar / wind subsidies are effective since the bulk of their cost is up-front, so you can generally rely on getting full value out of those subsidies.

Subsidies can certainly delay things at this point, but it's hard to see how it'd stop it.