I got a mailer from Midco this week. During 2010 and 2011 they'll be doing a digital upgrade. Analog channels over 22 will be going away, replaced by digital channels, to free up more bandwidth for HD, On Demand, and Internet.
They'll be sending more info later, but this mailer said most customers are eligible for two free digital adapters (free rental anyway). I'm guessing/hoping/assuming that the digital channels will not be encrypted, so TVs with basic QAM tuners will be able to pick them up.