My game library is archived on two external 4 TB SSD's. My niece and nephew already have the password and login just in case. Steam can't stop me on that, much as they'd like to. Single-player and couch co-op games should be treated like books or movies. Once you buy it, it's yours to keep, sell, or trade.
Live service MMO's are obviously different, but even there, if you've got an annual subscription to a game, that should be transferable for the remainder of the subscription.
