I don't think subsidies will be the driving force behind electric vehicle adoption in the US - the lower tax burden and higher discretionary income make them less relevant, especially against the car & status symbol culture. Some of my climate change denying family members switched to a Nissan Leaf some years ago for financial reasons, even with an hour long hilly commute with ~3k feet net elevation change. They got a plan that gave really cheap power at night and really expensive power during the day and came out way ahead even before including the state subsidy - although they drive their cars for upwards of 10 years so the subsidy was a sweat cherry on top.

I think the driving force behind EVs long term (decades) will be power companies trying to balance the grid between peak and non-peak loads. What better way to install massive amounts of expensive storage than to put their finger on the scale to incentivize their existing customers to pay for it themselves, all without hurting profits? The big thorn is that the infrastructure to support that is pretty much nonexistent, but there are plenty of steps in between such as smart chargers that only charge the car when signaled to. In California alone, there is potential to sell hundreds of thousands of electric vehicles that can provide backup power during the ridiculous number of blackouts we've had and will continue to have for the foreseeable future as the utilities upgrade their innumerable fire starters (utility poles).

Unlike Europe's highly integrated grids, the ones in the US don't have a network of aluminum smelters, pumped storage, and other industries set up to take advantage of variable power pricing with high enough density. As the variability between peak power production and baseline consumption throughout the day increases, I predict we'll see other more stealthy market incentives push people towards electric cars.