No consequences for kids doing it. At the end of the day it's hard to prove. One thing to keep in mind is that the IHSAA expects self reporting when school representatives become aware of an issue. The IHSAA simply does not have the resources to investigate much at all. What tends to happen from what I have seen is that kids and/or parents will slip up while trying to transfer. I know a few kids and the parents from years ago that were asked why they want to transfer, and they say "to play football".....or whatever sport. The message from the IHSAA is clear to schools, once that happens, the process ends. yes, I am aware there are loopholes to get around that...and that does happen too.
But with something like 3,000-4,000 athletic transfers filed with the IHSAA, like I said they just do not have the time or resources to really investigate unless something is glaringly obvious.