What If...
Hanna-Barbera chose to produce The Avengers (instead of, or, hey, in addition to, the DC-based Superfriends) ?
It could have aired on NBC or CBS during the 70s - 80s time frame, if it was produced concurrently with Superfriends. Back then, HB did produce the short-lived Thing solo cartoon while they also were producing SuperFriends on the ABC network.
It could have been great to have some Avengers cartoons produced for TV back in the 70s going into the 1980s. So many Marvel based franchises, solo or team-based, went for years and decades without anything newly produced. Gen Y and Gen Z folks kind of take for granted the stuff that's available in modern streaming and cable-network-based availability.
If the show started circa 1973-74, I could see core characters being Captain America, Thor, Iron Man, Wasp, Scarlet Witch and Vision. I could see other characters cycled in and out like Hank Pym (Yellowjacket?), Quicksilver, Black Knight, Vision, and Beast. The plots would in retrospect be overly simplified, but still enjoyable from a kid's viewpoint.
Spider-Man & His Amazing Friends was dramatically under-ordered by NBC during its run on the network, spending the last couple of years there purely in reruns. Unfortunately, we'll never know if more could have happened with more generous network liaisons back then. It could have been incredible to eventually see a syndicated package of 65 episodes of that show.
We never got to see the original Captain Marvel interact on Super Friends, presumably because the Shazam! characters were licensed to Filmation for the 70s live action show (and eventually, the short lived Kids Super Power Hour shorts in 1981.)
A fully-realized Fantastic Four cartoon, with all four original members, in the 1970s and 80s would have been great.
by the late 70s, Defenders could have been a partner show for the Avengers, focusing on the team of Silver Surfer, Dr. Strange, Namor and Hulk, with other guest heroes from that world rotating in and out. Daredevil, Power Man & Iron Fist could have been featured in particular.
It's too bad that a "traditional" Teen Titans show was never produced in the 1980s era heyday. that could have been cool. Imagine if they had the same animation as the production team behind the syndicated Bionic Six television show.
In the 1980s, when Hasbro struck a deal with Marvel to produce comics for GI Joe and Transformers, not to mention the partnership to produce the cartoon shows, it would have seemed like a no-brainer to strike a reciprocal deal to produce a syndicated cartoon show(s) based on Marvel characters, and even toys-- but of course, in the midst of this, Marvel strikes a deal with Mattel to make the Secret Wars toys, which fizzle out after barely 2 years.
Too bad that the original Avengers vs. Justice League comic book one-shot fell apart; it could have been, at the time, a great opportunity to have a seemingly once-in-a-lifetime opportunity to produce an animated mini-series or telefilm based on that.
The Pryde of the X-Men pilot apparently didn't spark a commitment (from whom, exactly?). It's too bad. I actually liked that episode's animation vs the 1990s show, as popular and influential as it became. I would have liked having at least a few seasons of that 80s incarnation.