Yea, a lifesize replica of some the Modern Warfare maps would be cool.
The problem for a local paintball field to pull something off like that is actually very expensive. The one paintball field 'n visit regularly does have many types of fields, and they also specialize in milsim type games. I know they spent a crapload of cash on their D-Day field back in July. Granted is not MW, but heck the field is cool with trenches and pillboxes and shell holes. It reminded me of the original call of duty games. You can try to google for U-TAC and D-day, to get an idea of the field. I know some people also uploaded some footage onto youtube.