at some point they’ll be autonomous, running off of IMUs and SLAM. there won’t be anything to jam.

Disclosure: I work for a company in this field.

They are easy to jam if you don't mind also not having GPS, Wifi and 3G/4G/5G service. You can do selective jamming but this is much more sophisticated

More sophisticated actors can fly on vision alone.

Disclosure: I also work for a company in this field.

Only if you see them coming; if you have to run the jammer at all times, that's just a homing beacon for drones.

You can run decoy ones as well. I think we’ll see a drone defense industry pop up soon

It exists, mostly defense contractors though.

https://www.theverge.com/2019/1/5/18169215/london-heathrow-g...