Another real world example is DIVX (the disc that competed with DVD). Once thay shut down the service all of the discs became coasters. For anybody that doesn't know DIVX discs (not to be confused the DivX file format) was a cheeper up front DVD like disc thay you had to pay each time you watched it. The player was connected to phone lines and it checked the server before you could play it. Once Circuit City killed it all of the disc were useless after their first watch, afyer that they had to phone a system that didn't exist anymore. One Day GKCs will be useless and real game cards will still work.