In Europe you can be sure that the trunk opening will be a sore spot in every Tesla showroom. It will not be a comparison to Model S, it will be a comparison to their existing car experiences. Rear headroom is often not so interesting, backseat is for the kids.
Not all will care, of course (there is some market for sedans, also some EV early adopters just won't care no matter what), but the size of the trunk opening of any car is a hot topic in general. That is why basically all manufacturers launch both sedans and station wagons, or even all three, sedans, hatchbacks and station wagons, all at once in Europe.
I can definitely see some families coming in and opening the trunk and saying that's a no go. Definitely.
Much less so with Model S.
That said, lacking competition and choice, Model 3 will of course sell nicely even with a sedan trunk. It just would have been an easier sell and a better car for the European market had it been a hatch like Model S.