Why would an American chose CHL over USHL? One of the main reasons is to play with and against the top talent in the country. If all the top talent is leaving after 1-2 years that is one less reason to go there....how?
Obviously the NHL and USA hockey do not want the USHL to disappear. They will be providing money and more support starting next season. If the USHL catches up to the CHL with amenities and player support, and the CHL no longer retains the top guys for more than a year or two, it becomes less of a reason to go there.
This is obviously just theorycraft but the possibilities are vast and the way things play out who knows.