Excited for the new changes that kernel 5.12 and 5.13 bring. Especially NVidia+Wayland and the hotplugging of AMD GPUs. Let's hope NVidia will follow soon with this functionality (but I doubt it).
is the hotplugging for external gpus, over thunderbolt or something?
piggy-backing -- is there a use case for hotplugging of GPUs?
Yes, Windows uses it for suspending discrete GPUs on laptops to save on power, for designs like surface book, for external GPUs and some more server scenarios.
I have a macbook air with an egpu connected by a thunderbolt 3 port. I unplug the gpu when I want to take the laptop somewhere, and plug in back in when I'm at my desk.