I'm sure there woud be interest in such a game - you just can't really expect people to get too excited until you have a bit more to show them.
Personally, I'm a huge fan of the original two X-Com games, and while I consider them almost perfect, I'd say there are two keys things that stand out for me:
1.) The combination of squad-level tactics with strategic gameplay (the geoscape-based portion of the game). If you want to see what X-Com would have been like without the strategic layer, you only have to look at Laser Squad (the game to which X-Com was originally intended to be a sequel) or any of the Rebelstar games - they're nowhere near as good, despite the tactical combat being relatively similar.
2.) The theme. X-Com had a really unique and interesting theme, with fantastic alien designs and excellent presentation. Fantasy is okay too, but avoid generic fantasy. Similarly, you need a unique and distinctive visual style - that's more important than the actual quality of the artwork / 3D models.