My only fear would be losing the game. Or accidentally breaking it. These aren't the size of our carts from yesteryears.
As long as it plays, and works... Does it really matter if it's on disc, HDD, cart? Makes no difference.
But, I guess Disc based games demand being put back in the case when not in use... So would these tiny carts, or cards... whatever we're calling them. Perhaps I'll finally like a nintendo console enough to buy it when this thing comes about.