I really don’t think that everything that has been speculated at is going to come in one huge pack update. I believe Valve will probably release all of this stuff in 3-4 updates. The first two will be separated out by content type (i.e. Meet the Pyro & “MvM game-mode” update) Everything else that did not make it will go into the next Manniversary update, Scream Fortress or Australian Christmas update.
The reason why the “replay update sequel” has yet to come out is due to the fact that it ties into another major update (which is not ready to ship). The other problem is that every year has technically surpassed the previous year when it comes to updates. So this year might be more overly ambitious and might actually bog down the development speed.
Also the new game-mode will probably outshine the other 3 game-modes we have gotten in the past. I’m looking at you Arena, Medieval, and King of the Hill game types. It will possibly be on the same scale of Payload, in terms of the time it took to make that game type. You have to remember that Payload was still being developed even prior to TF2 release.
As far as the secret map goes I have a feeling it could be anything. Many secret movie projects use a different alias to fool their fan base. I would not be too surprised if this is going on with this map. Right now “TF2 maps” is now barley wrapping up their payload map contest, which to me would be more interesting to see at this point. Considering they have been used as a reference point for talented community maps that make it in game.
At this point I am happy with TF2; because if I turn my head to other Valve IP franchise’s like portal, left 4 dead, counter strike, and day of defeat it’s not the same content wise.