They are going to keep the servers up, but this is only until the release of TU. Once TU gets released onto Steam, they are going to shut down the GMT servers (hopefully to make them TU servers!).
As far as bringing back the Lobby 1 map, I can only echo what the others have said. They won’t be making an effort on updating anything with GMT, so bringing back Lobby 1 for one of the servers isn’t going to happen. There are quite a few things that have changed and been added between the end of Lobby 1 and the release of Lobby 2, so they would still need to update the map with some things.
These features probably weren’t removed, they were most likely broken as either the Source engine updated, Garry’s Mod updated, or as GMT itself updated. As such, reverting to an old map won’t fix these features.
I hope this answers any questions you might have had.