Screw that. The band is going to be clear well into 2020. Even the 700 MGhz band has not been fully utilized yet and that auction happened quite a few years ago. Anyone who buys the licenses for these bands has to factor into their development plans existing product legacy. There is no way for news of the change to reach everyone who might have a wireless mic (churches, schools, DJ, casual musicians, karaoke home users, amusement parks, fair grounds, etc.)
The law won't apply equally across manufacturers and end users. If you're in the business of making, selling, renting, or commercially producing then your liability regarding the change is greater than if you're a pastor of a small church who knows nothing about pro audio and never reads trade magazines or junk male from installation companies. For users like these it comes down to attrition of the legacy product. You won't be able to get it repaired.