1. The fact that they keep selling suggests there's still a significant market for those big IPs. If there wasn't then they would have to significantly reinvent/reboot the franchise, but even when they do evolve, the single player games haven't gone completely multiplayer or sandbox.

2. Either way, it sold better than Bethesda's expectations with very little marketing. They now have a franchise because of it.

3. You're missing the point. What do you think the budget for those games was? The whole point of the OP was that publishers should focus on multiplayer games to make money. Both multiplayer and sandbox games require much higher budgets than the games mentioned above. They've still sold well enough to make a good profit and with none of the on-going maintenance costs of multiplayer games. 

The franchises mentioned above are relatively new (with the exception of Wolfenstein which has been practically dead as a franchise for numerous years), low cost and should more than meet the criteria you've arbitrarily set out. Instead of moving the goal posts to meet your argument why don't we look at sales of some of the big linear single player titles like God of War 3 (5.2 million), Heavy Rain (3 million), Bioshock Infinite (4.1 million) or Deus Ex: Human Revolution (3.4 million). Those are physical sales only so with download you could probably add 0.5-1 million to the PC versions (where applicable).

Linear single player games are still as profitable and still sell well.

There is more than enough room in the industry for many types of games.

Titanfall was one of the easiest games to market. Simply mention "From the original makers of Call of Duty". It might be a new IP but it's not like it didn't have pedigree or hype. The developers themselves were practically a franchise on their own.

The single-player equivalent would be a game like Red Dead Redeption (from the makers of GTA).

But there's also not enough room in the industry for endless variations of one single type