[JMT1985]

I doubt we will see David or Catherine back again - if RTD does go down that path, it will be the case of ever diminishing returns and the viewers will get bored.

Remember that David was in the 50th in 2013, then a decade of waiting and he returned for 60th, if the show is still going by 2033, that would be a time to wheel David out for the 70th, and probably he wouldn't have aged much, as David seems to be unique, he looks always fit, healthy and fantastic