After Arkham, Black Flag and GTAV, is this the end of an open-world gaming golden age?

Assassin’s Creed IV: Black Flag can easily see you through to the new year with its heaving open-world of missions and quests. You could put hours into Arkham Origins over the winter weeks, too, hunting for all the snowbound secrets and swooping down on rampaging thugs. Then there’s Grand Theft Auto V, with its generous…