John's the jedi, but I would think that:
no cell plan=no cell communication for over the air updates. If your system has the firmware version that operates without bugs, then the system will continue to operate correctly whether there's another firmware update or not.
I know you've had some system issues Teeder. Hopefully you've got them worked out and can see the value in the system now. I've had plenty of issues, too, during the last 7-8 yrs of ownership, but eventually have solved them all.