Apparently such gear is going to be illegal to use at some point. So, uh, what happens if you continue to use it? Will there be FCC gendarmes stalking illegal wireless users? How do I known when the phase out affects my area? Are there narrow sub-bands within this spectrum that will continue to be available?

The Friendly Candy Co has changed the date a few times already. But it appears (now) to be July 2020. Interference is probable before then though and in some places already.. There is also a guard band in there that will be legal under 'circumstances'. RF power, ect. As I recall less than 20mW (search),

"A bipartisan letter led by U.S. Rep. Cathy McMorris Rodgers (R-WA) called for the 600 MHz spectrum recently offered through the Federal Communications Commission’s broadcast incentive auction to be cleared by the scheduled date of July 3, 2020."
https://riponadvance.com/stories/mcmorris-rodgers-leads-bipartisan-letter-calling-fcc-clear-auctioned-spectrum-time/

As noted above, it depends. There is no clear concise answer. Wireless companies do offer information and in some cases incentives to move to systems not in the 600mHz band. Their motivation is, of course, future sales.

600 MHz Wireless FAQs || Audio-Technica US (http://www.audio-technica.com/cms/site/16505e589e0be6c8/index.html) is but one of the sites with information.

The so called a "duplex gap (652-663 MHz)" and the "guard band (614-617 MHz)" and channel 36/37 below 614 mHz MIGHT still be usable in the future, if your system is able to operate at those frequencies. But that speculation should be verified.

Video wireless systems are very low power (the ~300 ft. range says it all), so if in the middle of nowhere (some would say Albany is close) it is not likely the spectrum cops will be sniffing around, But interference is a possibility even if FCC is unlikely. (No one wants to have teenage chitter-chatter in their wedding video.)