We wouldn't be able to coordinate it and it's very unenforceable. But, it doesn't really achieve parity anyway. Only way that could happen is if we were restricted to 18-19 year olds (which would amazingly cool). That's super unrealistic due to the limited supply, though. Hell, there aren't close to enough potential senior NT players available for even the original 18-25 year old scenario to ever work. Let's be real, not many Naismith teams would be super interested in training players under perennial allstar who have no real ability to make the senior NT squad or be a quality role-player on their own club team.
For training, we just need to make sure MVP+ trainees get into the hands of quality managers -- very preferably Canadian ones.