Right now to go to work full time they have to get an H1B, which means they'll get screwed over if it becomes a matter of who pays the most.
The US loses if we educate kids on things, and then they move back to whatever country they came from. I mean, it's good for the country they go back to, but if we're looking at this in a self-interested "Good of the US" standpoint (Which we must be, if we're having this discussion at all), we want to keep them here.