Based on what I'm reading, they will sell the station, but keep the rights to the cable distribution of the channel. Not sure exactly how that will work.
It's a pretty interesting situation, the FCC now allows TV stations to keep their "must carry" status even if they turn in their OTA spectrum to the FCC to be auctioned off. It's a total win-win for CBS... they keep 2 stations on basic cable and get to keep all of their radio stations, and as a bonus there's no longer a physical transmitter plant to maintain for WLNY.
It may be more complicated than that. In reading through the FCC's lengthy and dense Notice of Proposed Rulemaking on the incentive auction that was released recently, there's nothing explicit about maintaining must-carry for stations that have returned their spectrum entirely.
But by virtue of owning WCBS-TV, CBS still has plenty of leverage to get cable companies to carry "WLNY," whether or not there's any licensed station associated with the "WLNY" programming. They wouldn't even need to carry "WLNY" as a subchannel of WCBS-TV's OTA signal, necessarily.