Today's US pornstars also mostly do porn to raise their profiles and thus their escorting profits. One hour of escorting (which is like 20 minutes of fucking) can pay them the same as a whole day of shooting porn and they can do multiple clients in a day.
Unless there's a new witch hunt on western porn studios I don't see a western jav import boom in the very near future. 3 major barriers for that: mosaics, the women(lacking in variety), the language. In the longterm japanese politics can eventually end the mosaic and technological advancements should net us free computer-generated subs.
In the short term I do however see western porn having to start imitating the creativity of japanese porn, particularly as the generation that's already growing up on internet porn grows sick of their wives.