I don't think digital interfaces age poorly -- I think bad interfaces age poorly.

And I think there are more bad digital interfaces because most appliances/objects have been made in the digital age.

Video games might be a good case study here. Some game interfaces age really poorly, while others don't seem out of place at all.

As far as digital/analog hybrids are concerned, take a look at synthesizers. One can hardly discern modern Casios from their 1980s ancestors.