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.
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.