This is what I'm thinking too, if there's any merit to the rumors at all.WhiteTigerShiro said:My money is on games being only valid on the specific 3DS from which they are installed from. If you try to take the cart and put it in a different 3DS (or if you try to copy it and give it to your friend for his 3DS), then it won't work, giving you a message to insert the cartridge into the system for which it was validated. Or maybe the game just won't appear as a selection, but the cart will still show that it's eating-up some memory.
When you install the game, the cartridge is disabled for all other 3DS units until the game has been uninstalled again and the cartridge re-inserted into that piece of hardware.
Preferably there should be a way to look at the cartridge and see if it has been hardware-locked, but in the worst case scenario the retailers will simply have to do a quick test for every returned and otherwise pre-owned cartridge. It's not that different from checking discs for scratches.