I'm currently reading Col Hammes' "The Sling and the Stone" and though I'm not totally convinced that you can define warfare through generational parameters (nod to Clausewitz's idea of "war's inherent chaos") I certainly agree that the prevalence of state-v-non-state wars since WWII is a significant change.

The way warfare is waged is certainly changing and key to discussions on modern warfare (I find myself in agreement with Hammes on this) is the rise of the non-state actor as a result of globalisation and expanding networks of communication.

On the issue of the rise of non-state actors, I'm wondering how far along this phenomenon is going to develop. Are we going to see states completely usurped from their position of primacy in the international system? Will they continue to have a monopoly over violence? Is conflict going to continue to de-centralise wherein mankind returns to pre-Westphalian conflicts of multiple warring gangs and factions?

Combine this with increased climate and resource pressures. Will increased desertification exacerbate the risk of ethnic conflict within states as we have seen in Darfur? Will so-called "climate refugees" and the movements of climate-affected peoples across porous globalised borders create factionalised conflicts over resources and land? How is all this going to fit into a world that is running out of oil?
It's never a good idea to get your Zen out of Hollywood but is "Mad Max" what we're going to see once we run out of oil?

If we go off the generational model (which I still have issues with anyway) is 5th generation warfare going to be wars of climate and resources fought between powerful sub-national factions within post-globalised "token states".
What will the role of state militaries be in the milieu of this? Peacekeeping? Fighting the "Three Block War".

Doesn't sound like much fun for anyone. Thankfully these are all extreme hypotheticals.