Note this quote is from another thread:
IMO …
Full bore tooth and nail combat simply can’t last more than a very few years before munitions and the treasury are both exhausted or one side is decisively overrun. But …
Modern industrial warfare can also be left in a low intensity barely ticking over mode for decades. Trading irritant level destruction that largely hobbles the economic potential of the area in dispute. Or it settles into a fully frozen conflict of hate, guerillas, and the occasional little green men.
The limiting factor for an e.g. 80 years war is more likely political now.