No doubt the push for an always online model of a game doesn't translate well from a single player focused game. The two attempts by Bethesda is probably why it's taking so long for a sequel.

Which is funny because two of my favourite multiplayers of all time were additions to single player games: Assassin's Creed Brotherhood and ME3. Interesting too they seem to backing off making it Xbox exclusive, seems the marketing see's the backlash that might cause and decided they'll make more money long term making it for all platforms.