Consumer-grade drones and RC ground vehicles becoming a major part of a war between regular armies.
https://www.orwellfoundation.com/the-orwell-foundation/orwel...
And it is very interesting watching the smaller (comparatively) country of Ukraine hold their own against a much much larger force in large part by using $50 Walmart drones with a grenade duct-taped on.
The large-scale use of cheap drones is going to change warfare tactics forever. It also leads to a bunch of fascinating anti-drone weapons, and then, of course, drones that can evade or are immune to such weapons will follow.