Depending on how many games they have in their "Vault" at any one time, I think it has potential.
As a casual sports games fan, I wouldn't mind messing around with Madden 25 and FIFA 14 for a month for $5. I don't need the latest and greatest iterations of the games. Just play a few games, grab some trophies, and move on. Also Peggle 2 and Battlefield 4 single player can EASILY be beaten in a month, rendering those games basically $5 as well.
Not to mention if you have an impromptu house party and want to play some Madden or FIFA, it would only cost you $5 to get that going.
I'm definitely jealous it's Xbone only right now.