In the US "capability" (even when we don't actually use it) is such a huge sell for many that I don't think were going to see a cultural shift to buying a smaller class of vehicle as you switch to EV. If anything Americans buy up as the operating costs go down.
EVs mean more power, more AWD, more cargo room than comparable ICE vehicles. More "capability", as you say. At the same time, the reduced range discourages going for a larger, bloated vehicle you don't need.
I can definitely imagine a lot of the families that have a crossover / smaller SUV now deciding to go with a sedan like the model 3. It has all the cargo storage they need and has the power / AWD they are used to.
I think you are right that some people on the margins may step down instead of staying flat or going up given features like frunk space (although model Y sales are beating 3 sales despite the reduced range and increased price), but AWD models of the 3 still weigh more than many AWD crossovers. Stepping down means a huge hit to total cargo volume and cargo height moving to a passthrough trunk vs a cargo area, and you also lose ground clearance that people think they will need for their yearly camping trip.
American car purchases have been trending bigger and bigger and I don't think a frunk and fast 0-60s is enough to buck that trend.
Even among those lower price points, the trend seems to be towards heavy SUVs/CUVs. Also, it's pretty clear that an equivalent car will be heavier as EV compared to it's ICE variant - the added weight of the batteries is a lot more than the weight saved by the electric engines. This is especially true for lighter engines with smaller displacement.
Now, of course there are some really small one or two seater EVs, but those also existed as ICEs and I don't think anything indicates that the majority of people will suddenly prefer smaller cars just because they buy an EV.
You got to try to zoom out and understand the pro/con of different options.
Good or bad, we have the society we have. I need to drive my kids to school. To do so safely, I need a large car. Would it be better to live in NYC and take the subway? Or have denser walkable communities? Sure. But in the meantime, the kids need to go to school.