I think that's well beyond minimum spec. Empires is not your average 2016 RTS/Shooter. I think empires uses about 500MB RAM, last time i checked in task manager...
With improved model's, texture's and general source code. The requirement's will be more demanding, especially for large scale FPS mod's.
Well, yea. It would be. However, we are still lacking the improved models, textures, and general source code so for now I think that what you listed should be the "Optimal" specs.