Do you already have ideas floating around for the possibility of another Elemental entry? I can keep a secret
It all depends on how well this game does. As long as people want us making fantasy strategy games, we aim to provide them. 
So far, we've made Elemental: War of Magic - which was a commercial success but a critical failure. Then we made Elemental: Fallen Enchantress which did well and was generally well liked but didn't sell as well as WOM (since WOM had gotten a lot of pre-release coverage). Now we have Fallen Enchantress: Legendary Heroes.
The next game would be like Fallen Enchantress. A new entry for the game universe that shares some basic design elements but goes down a new path.
I'd like to see more diplomatic and a LOT more faction differentiation (both visually and mechanically). I'd also like to see the magic system revisited right from the start. But like I said, that's more of a "in the future" thing.
Legendary Heroes is likely to be *THE* last word on Fallen Enchantress with future enhancements via free updates funded by DLC additions. So LH will continue to evolve but it's not like one day there will be an update where there's a new magic system. 