There's actually a much simpler solution and in a way they are already using it on the 360; require the disc to be in the drive if you want to play the game offline outside of the activation period.
<Cue guess mode>
The issue is again that the Disk is worthless, and only used as a download vector. My thought is that MS is getting rid of Disks as an actual game 'entity'. You are buying the activation code, and the cd-key. The disk is
purely a download vector, and offers no validation of any kind about the validity of your access to the game itself. A disk is worthless without an associated account.
The signed 'ticket' route makes a certain amount of sense in this state, as it:
also allows you to play offline
guarantees publishers that you can't sell the game while still being able to play it
allows you the ability to sell a game on an online marketplace very easily
allows gamestop to resell games and take a cut (if necessary, basically have validate your sale through them--though this scenario is much less likely)
allows you to play games on other machines (simply login, and create another game-ticket).
Issues:
Purely offline devices on other machines. You can't simply walk over to a friends house and play a game off of the disk without logging into Xbox Live. This might be worked around by having some offline ticket vector (USB key? or external harddrive perhaps. Tote around your pluggable HDD to your friends house, and the ticket is in the same install as the game. That seems plausible to me).
What happens when XLive services are kaput. My solution would be to switch to indefinite tickets for all owned games on your console. You couldn't buy a new one, but at least all games you own would be playable from your machine.
Another issue is of course when people hack your console, but again that's going to happen no matter what..so I doubt publishers/ms can really do much to stop it.