No idea how Treyarch is going to do it. The last time I played COD long enough to encounter map packs, they included it in the regular playlists but would just interrupt us peasants with "you don't have this map pack" messages whenever a DLC map is loaded. As a result, the game is loaded with a number of players missing because they didn't have the map, so the game booted them out.
And seeing how there is voting and not everyone will have the map packs, people may not vote those maps to be played so Treyarch may create a separate playlist with just those maps so people actually get to play what they pay for.
It's never elegant. It's times like this where a server browser would be beneficial so you can just play with people who have all the maps or none of the maps. (I guess you could make a special playlist for season pass holders that prevent non-season pass holders to enter as well)
