Haven't seen one of these in a while. The short answers is yes, a reboot will solve it.
Metaspace gets used up when apps/drivers get loaded but also when some Groovy dynamic features are used. It's an incremental process, and running a hub for a month+ while doing development can fill it up. Large apps/drivers create a metaspace use spike when compiled, but it usually goes down (if not entirely) after a few GC cycles.
Interestingly I use a C7 for development and that gets absolutely hammered and abused considerably, I don't recall the last time that got a reboot .... probably when I installed the last firmware release when it dropped.
The C4s on the other hand are my production / live hubs so I only tend to deploy drivers there once they're done. So that only happens occasionally. I guess the lower specs of the C4 mean it's more prone to the issue.
Is there a chance it will recover to a point where I can save this drover? Or is a reboot the only way out now?