Reportedly his son Chris Candy will have a cameo in Spaceballs 2 as “Barf Jr”.
And maybe Constantine will get one, although I’m not sure who else besides Reeves might be in it.
There’s an IMDB entry showing Reeves and Peter Stormare as the only two cast mentioned.
Roy Kinnear very nearly died during the film too. He fell from a horse and sustained injuries that he died from the next day. His son looks a lot like him though.
It has a bit of steam at this point. I’d say we’ll see Constantine 2 by 2030.