For Rogers customers that still connect their cable directly into the wall, they will gradually lose the ability to watch certain channels, until eventually they will lose access to every channel. This also can manifest itself with channels with poor or non-existent volume.
Digital Adapters are definitely an option to allow Rogers customers to get access to some of the channels - at least the lower tier ones. However, to really get the full advantage of cable with Rogers - even Digital TV (what Rogers used to refer to as "Basic" cable), I always recommend to my customers to get Digital Terminals. While Digital Adapters are cost-free and do restore some of the lost channels, only a Digital Terminal - even just a Standard Definition one - will allow access to things like Timeshifting, Rogers On Demand, Stingray Music, The Aquarium Channel, Premium networks, etc.
In effect, with a Digital Adapter and Digital TV, you are paying for at least 50-60 channels that you aren't getting access to.
Actually, the aquarium channel is the only one I get here now connecting directly to the wall.
There is a thread somewhere here where a customer subscribed to the Digital Plus package could not receive HGTV and a couple other channels with the DTA, even though they were in the lower numbers. He finally had to accept that he'd either have to get another digital terminal or upgrade to VIP to get the channels with the DTA. There are always these nagging inconveniences designed to get you to spend more money.