probibly will go out with entrenchment as one

or the three mini expansions on shelves

or the game and the expansions as the final edition

It would be nice and they could include some special GoTY stuff like an exclusive theme, units or item.

I think from a business perspective that a GOTY repackage would be profitable.  If you lets say hypothetically repack entrenchment with sins in 6 months, sales on the additional expansions would increase as well.   Not everyone keeps up with industry awards and every bit of exposure helps.  Put up those accolades on the sins site to let new people know as well. 

For the record I hate wrestling but this old time favored analogy of mine seems to fit.

You got the title belt there Hogan.  Time to rip the shirt off and flash them guns!

The GOTY shouldn't have any special content or additional units or anything like that.  Rather, it should be updated out-of-the-box to the latest patch and include some extra maps (that anyone who has the game can download).

The idea is to just produce copies of the game in new packaging that points out that the game received several GOTY awards and to then get it back up on store shelves and let the game (and not new content) sell itself.

I'm not expecting it, but I don't see why, with map authors' permission, they couldn't be included.  On the otherhand, I can see how it wouldn't be worth the trouble nor the potential legal issues.  Maybe they could add an auto-download feature for custom maps which would bring customs to online multiplayer.