As a theoretical concept, the Toobworld Dynamic works. In practice, we've seen it in action many times - a Western crossed over with a cop show. A sitcom that gave birth to a drama series. And then there's the TV cop who appeared in about nine different series (including a cartoon), over four different networks at least.
The Toobworld Dynamic is a visual world, unlike some of the other shared universes which can look beyond such problems as recasting. But sometimes the possibilities of the crossover should be left to the mind only.
This version of the new "Avengers" movie - using the 1970's TV counterparts of the super-heroes - is a good example. On paper, it works......
Of course, once you get to Hawkeye, the Destroyer, and Loki, it does get a bit silly (although Paul Lynde does rock the horns......)
Over in some off-shoot of the Cineverse, this 1940's version of the Avengers works better:
I could see the Rocketeer fitting right in with these people....