The thing everyone needs to remember is that digital TV is not HDTV. Switching to digital for most small market TV stations involves installing a new transmitter. Not much else changes unless the station wants to buy new HDTV cameras, switchers, tape decks, etc. A lot of small market stations don't have that kind of budget. So they'll go digital, but not necessarily HD.
Digital transmitters are more expensive, to be sure. And so are the antennas, cabling, power supplies, etc. But they typically cost less to operate than analog transmitters because they use less electricity, so for a lot of small market stations it'll mean some relief for their budget. Of course, that typically also means more money in the pockets of the owners, because they'll not likely spend the money on infrastructure improvements or pay raises for their staffs.
To be sure, there are some really small market stations (below market size 200 or so) that probably can't afford to go digital, and they may go dark. But there probably aren't many of them, and since LPTV stations don't have to go digital, some of those small market stations may go the LPTV route.
