1. Map Editor/Mod Tools
One major complaint about XCOM:EU is the lack of map variety, especially from people whove played multiple times. While Firaxis promised mod support in the pre-release media campaign, it hasnt really materialized so far, hurting the PC community in particular, which thrives on modding. If theres going to be any real longevity for the next XCOM, a map editor must be available on or before release, if only to start building up a catalog of levels for future players. Getting more comprehensive mod tools would allow players to expand the scope of the game by adding new items, new enemies, or even new mission types. They would also enable people to create total conversion mods, building whole new games on top of the turn based strategy framework that XCOM provides. User generated content could keep the next XCOM alive for years, and for Firaxis, thats too good an opportunity to pass up.
Is there anything you would like to see in the next XCOM? Feel free to drop it in the comments below.