They're already trying to batten down the hatches about the used game thing:
While Phil [Harrison] discussed many potential scenarios around games on Xbox One, today we have only confirmed that we designed Xbox One to enable our customers to trade in and resell games at retail," a Microsoft rep said. "There have been reports of a specific time period — those were discussions of potential scenarios, but we have not confirmed any details today, nor will we be."
EVERYONE KEEP QUIET, DON'T GIVE THEM ANY DETAILS THEY'LL FORGET!
Xbox One - the number of times you can install the game.