While new maps are always a good idea, I'd like to see a dynamic component to the maps - something more than the shifting of strategic bases to the rear.
Assume multiple base types - S Dirt Field (similar to what we just had in FSO), S Paved Field, M Paved Field, L Paved Field. I'd love to see multiple layouts for each type, but take what we can get. Put some restrictions on what craft can up from which base type (something simple like no 4-engine bombers on a small field, no jets on an unpaved field, etc.)
Add the dynamic component that bombing a base FLAT makes it respawn as the next smaller base type. So bombing a Large Paved Field flat makes it respawn as a M Paved Field, bombing a M Paved Field makes it respawn as a S Paved Field, and bombing a S Paved Field flat makes it respawn as a S Dirt Field. Bombing a S Dirt Field flat just shuts it down until it respawns as S Dirt Field. As a further dynamic component, the spawns from each base type at each location could also be adjusted - so bombing a S Paved Field with 2 vehicle spawns NE and SE causes a respawn to a S Dirt Field, but with only 1 of the 2 vehicle spawns enabled (this could be random, or could be set by the map maker).
At a certain interval (daily, hourly, ?) let the map have a "build phase" where some number of bases build to the next higher size, and enable spawns that were disabled by enemy bombing. S Dirt Fields get paved and turned into S Paved Fields, S Paved Fields become M Paved Fields and so on. I would limit this effect to a certain number of base builds per time period, and set a bias that S Dirt Fields become S Paved Fields before any other types of fields get a build in Size.
Over time, changes in base size and spawns should create new choke points and threats, as well as different offensive and defensive challenges to each country. This system can be expanded to ports or vehicle bases if we get S, M, and L base types for these as well.
Feel free to flame on or add some suggestions of your own.
