If the device was legal when bought, use it at your pleasure. When the feds offer to reimburse you for the cost of your 700 MHz unit or give you a mic set on a different frequency, then you have something to consider.
Several times the FCC has mandated changes to radio or television that turned a very expensive item into a shelf curiosity without compensation.It resembles eminent domain.
Once legal firearms have been turned overnight into banned instruments of evillll.And the list goes on.