You're confusing two different things.
Comcast has advertised that you need to do nothing about the
digital transition for broadcast channels. That was, and remains the case. Comcast is still providing the broadcast channels such that you do not need a converter box. Hallmark Channel is not a broadcast channel. It has nothing to do with the broadcast
digital transition that was the context of the advertising you referred to.
The movement of cable networks, like the Hallmark Channel, to digital, is a reflection of customer demand: Many many customers are demanding that cable companies provide more
HD cable channels. The only way to fit more
HD cable channels in is to reclaim bandwidth currently taken up by analog channels, which provide video that is less than 10% of the resolution of
HD but take up about twice as much bandwidth. Comcast is actually one of the service providers who have continued to provide channels like the Hallmark Channel in analog the
longest. Most of their competitors converted the Hallmark Channel to digital long ago (if they even ever provided it in analog). Comcast has balanced the needs of customers like you, who rely on analog, with the needs of
other customers who want things different from what you want. Until now, your need have prevailed, but as time goes on there are more and more of those
other customers, and they represent more and more of the business opportunity, and so eventually, even in Comcast, the needs of those
other customers will prevail.