You know the old adage about "making up on volume" -- well clearly the volume is gone. As you described it, this is a device which, now, people already have, there are practically no new televisions coming into the system that don't have one already, and the vast majority of people may never need another one. Surely a niche market, so the real question now is whether consumers will do their part to foster the niche market, i.e., being willing to pay a premium to make up for what, previously, manufacturers could "make up on volume".
I think not. I think once consumers see something for a certain price, they're not going to start paying double for just a few extra bells and whistles. And the availability of these boxes for dirt through eBay will further undercut consumer willingness to pay for a new, warrantied commercial device.
What I think we will see is a move towards integrating this capability into other devices, such as the Roku Digital Video Player -- devices where the ATSC tuner is just an added feature on top of the main purpose of the device being sold.