Where will this game be in six months? Still played by the modders.
At my experience, most of the people will not make a mod for a game which it is not played by the people. At other point, people will continue playing it, if the game adds by example, new mods more unique than the mods from other games.
But personally, SOASE should not die in the next 6 months, in fact large communities like this, usually they live ten years without new improves in the original game and here, we have seen a new patch very few time ago. If SOASE will give the same amount of hours playing than other games with mods, easily I would give to it another ten years. Unfortunately after some time playing, SOASE starts to be boring because it is very monotone but easily I can give to it two or three years more of live.
I sure do hope they will release a full blown sequel...
If it is a new game with a lot of changes and new features. Very good. But if it is a new game as Rebellion which it is more as a DLC from the original SOASE with a higher price. I would not know if I would be happy. Specially by the 2GB limit, even the older Star Wars Empire at War with the last defreezer program http://firefoxccmods.com/index.php?topic=1078.0 does not suffer this problem. SOASE developers should fix it if they want release a new game.
About other games similar to SOASE which they can move all the community to it, specially the modding community. I would not put my eyes in Planetary Annihilation because it is a very different game and it is focus in the ground combat, perhaps you can add some air units as space units but nothing more. At the end, the developers from Planetary Annihilation have not spoken too much about modding.
But I would put my eyes more in Vol'Talkes, a new game at development with a engine very similar to Star Wars Empire at War which it will be a game without ground combat in first place and it will support the modding community. The final game will be more similar to SOASE with a galaxy conquering planets. https://www.indiegogo.com/projects/vol-talkes-the-ai-war https://www.facebook.com/HyperDriveGames
They tried a fast kickstarter campaign without too many success but they will finish the game, just it will take a few more time.
About if it will add ground combat, if they let it, it will be after the first release with patch or DLC.