It actually wouldn't be crazy to say they may release 1 or 2 more maps for free. They did it with Forge Island. In the most realistic scenario, I could see a single map remake being released for free. --- The mind of the subject will desperately struggle to create memories where none exist... ~~PUT A LITTLE FENCE AROUND IT~~
According to the the anecdotal evidence of several players on this board, you aren't going to ever see the DLC in a playlist other than the DLC only playlist, because too many people simply don't have the maps. Take that for what you will. --- Perfection. Where everyone fails. If you expect nothing you can be happy for everything.
Games generally release their DLC map packs in quick succession when the game's population is dying off quickly, because they're trying to garner as many sales as they can before the game empties.
The fact that Halo 4 released all three map packs in under 6 months tells a lot for both the developers' and the players' faith in the game. --- Underwater Spartans: http://www.youtube.com/watch?v=Djp5dtz02eQ&feature=plcp