I do not know how much of a threat drones will be in future wars. I don’t think anyone really knows. I suppose it is something that the metanymomic Pentagon should worry about.
They’re a threat now. Russia’s been at it going on 4 years now.
If you think of the word "drone" as referring to pretty much any unmanned vehicle, then you can be certain that many different categories of drones will dominate, or at least influence, all future battlefields.
These can range from little quad-copters costing maybe $1,000, and carrying cameras or a grenade 10 miles, to $1+ million dollar cruise missiles that can fly 1,000 miles and loiter over a battlefield all day, waiting for its assigned targets to come out of hiding.
What's not yet known is how successful will militaries become in shooting down, or otherwise eliminating, all the different categories of drones.
We do know that Russians, and even more, Ukrainians, have a huge headstart on what drone warfare can look like on future battlefields.