Sometimes random ideas just pop into my head.
In this case, I was looking at Conan and noticing how much like an old man he can be. I'm certainly not the first person to make that connection.
What occured to me was an idea for a Mork & Mindy reunion.
In it, you cast Robin Williams as Mearth. Yes, I know he's actually older now than Jonathan Winters was in 1981, but since Winters always played as older - Face it, that's why he was cast! - and Williams can easily play as younger still, I think it would play fine.
You cast a preteen as an aging Mork, his faculties slowly leaving him. You get someone like Bobcat Goldthwait, who wouldn't be afraid to look at the dark or potentially taboo side of the situation and the Jocastan emotions it could bring up.
The whole thing works not only as the only real way you could do a reunion in continuity, but since a "Mork & Mindy" reunion is hardly something the universe has been calling out for. But as it also works nicely as a metaphor for marriages where one spouse becomes enfeebled while the other remains an active adult, I think it could actually be touching and funny.
And could almost justify the fourth season of the show.
Yes, I totally just took the time to write about an unfilmable movie based on a largely forgotten continuity point in a 30-year-old TV show. That's what I did.