GMOD 2?

I really doubt that there'll be some sort of "Gmod 2" without a new, serious addition to the Half Life series. Having something like Half Life 3 would add so many new good things to the Source Engine and give Newman a reason to remake Garry's Mod. Without a new addition to the series, there's not going to be a lot that comes from remaking the game completely.
If anything, they'll release an update that changes a few things. If there's no new addition to the Half Life series, then it's just going to be a cash grab because of how badly people want the old Gmod to come back...
Also if there's not going to be Lua integration, the modding scene is going to be really scarce. The addition of Lua and specifically GLua to Gmod was really the thing that made Gmod the most modded and moddable game of all time.