I can't wait for RoN. Firstly, its Brian Reynolds - the guy who helped made CivII and SMAC! Looking at CivIII, maybe RoN will have some of the feeling that's missing when we compared CivIII to its predecessors. Secondly, its a Civ game. Thirdly, I don't have such high expectations on it as I have on CivIII.
As long as its a an RTS modding the game would be possible... surely it'll be packed with a scenario editor. But I doubt units can be changed much.
like I said - I can't wait! I'm gonna buy it once it comes out!