I just finished up a game today on a gigantic map that took about a month to complete. I usually try to submit a game every other month or so, time permitting.
I think the community is still very much alive but admittedly not as active in the forums or the Metaverse/AltMeta as in previous years. People are still playing GalCiv II/DL and it's two expansions, DA and ToA as far as I can tell judging by the questions posted in the forums and scores submitted.
I'm still enjoying the game (currently playing ToA 2.03) and experimenting with new strategies and learning new things all the time which keeps everything fresh for me.
As far as the development of a GalCiv III game down the road is anyone's guess. After all, Stardock just released EWOM recently and I'm sure the focus and support for that game will be their major priority for quite some time to come.