Will this game receive any more, major additions/changes?

Hmmm, it just came to my mind - if you are not planning on making any more additions (now), have you considered giving some basic modding support? Guess there would be some people, that could (eagerly) make some great changes/additions, and you could even maybe add some (or all) those to the official "expansion pack", giving of course the original author some credits/shares/whatnot (whatever you'd find practical/fair).
That way you'd still continue developing your new game, while the old one (which still has great potential to unravel) could grow on its own, and eventually you'd profit from it anyways.