are there going to be areas on the map where flammable natural resources generate (i.e.: natural gas pockets, oil) that could accidentally damage the planet if ignited by battle? Or could be revealed later as the planet takes damage making the planet more and more unstable?
These kind of things are kinda gimmicks. I'd much rather the devs spend time improving orbital mechanics or sea warfare or other core features then spend more than peripheral effort on these kinds of 'flavor' add ons. Not that these things arn't worth value to a games overall 'polish', but I think this particular idea would be too time consuming for the benifit development wise. Perhaps just more basic surface damage, trees being flammable and such. With the engine permitting permanent deformation such as footprints and tire tracks perhaps we will see artillery 'digging' as well. How much of this sort of stuff that will happen is pretty much all time and money. I place it at low to very low priority.
We should probably make a Mythbusters mod. Your first step sets a shrub on fire. The shrub ignites a tree and it starts blowing up forests, rocks, mountains, moons, planets, suns, solar systems...
