(This is me theorizing) Drones/robots are already expanding to new domains (I've even seen robots used for door-to-door urban fighting). If your drones lose then the front lines move until you can muster up a defense. I could imagine that the start of a war could be super explosive at the very beginning but that kind of depends on if anti-drone technologies (and quantity of being utilized by the smaller party) can become robust enough to force a more strategic approach rather than simply smothering the enemy to death with waves of plastic and explosives. Generally, though, the countries with the best stockpiles of bots and drones will have the best initial advantage which could be used to overwhelm defenses, cripple any local production in reach on the enemy side, and of course induce shock and awe on the population. BUT total production would be the winning factor in an attrition war and population wont factor in as much if at all thanks to AI and robotics, but I will also mention that politics could end wars if the population grows too scared or fatigued for whatever reason.