Dynamic scaling of multiplayer maps

Playing multiplayer games off peak hours can be a frustrating thing. My current games of choice are Starcraft 2 and Team Fortress 2, both having issues when at lower player numbers (but SC2 is still in beta).

Joining a server in TF2 with a small number (<10) of players removes most of not all of the teamwork. Since one or two of the players on either team are also respawning at any given time, the game degenerates into something close to a team deathmatch game. If the offensive team ever has 2 more players than the other team they can also capture the point/intelligence/cart to move on to the next stage.

Instead of being forced to play on the big sized maps even with 6 players, why not create a system that lets you open and close off parts of the map depending on the number of players? TF2 might not be the best game as an example for map scaling, I'll use it here just because I'm intimately familiar with the maps and game mechanics. A better suited game might be Unreal 3 deathmatch but the concept still applies here.

The technology for creating this kind of maps is possible and almost but not quite possible to create in the current version of Hammer. Using models to block off entrances and using trigger_hurt to kill everyone in the enclosed areas works and is used for a single area on cp_egypt. Being able to tie terrain and geometry to a func_door to be able to lower and raise them is not possible, probably because the compiler can't sort out how to bake the lights. The biggest issue is of course that the map doesn't react to players on the server and the map doesn't respond to settings (choosing to play on full-size maps should be available).

Just closing off existing maps isn't the best solution either, maps will have to be designed from the ground up to support this. I still think it's a good solution instead of making separate maps for few and many players. That way you'll be able to switch between all maps no matter the number of players instead of only playing the small number that is catered for your preferred playing style. It might be worth looking into.