You know how in CIV III complete they had a whole slew of mods from the site that users made- seemed to me like over a hundred, but that is probably an overestimate. But it would be great if they did that we the biggest and best mods in CIV IV on this new Expansion pack. They probably cant, with it being nought but an expansion pack, but just in case they can.

There is Rhye's and Fall of Civilization. Also, there's the scenario based off of Fall from Heaven (I doubt they could put the real thing in there while still mantaining an E10+ rating).

Then again, Rhye's mod was updated for BtS if I recall correctly, and the Fall from Heaven scenario was built from the ground up by the FfH team. Your idea is more of a "special edition"-esque idea.

Theres plenty of mods in it already, many looking great.

If there's anything new to add, then it is already too late. Usually, up to 3 months before a release is the cut-off date for new features so that testing can get done.

Granted, that doesn't mean last-minute features don't get slipped in...

Yes, you wrote this probably six months too late.