Hey dndphilmont, long time no see...
I see you haven't yet given up on the dream of the One True Setting (TM) that combines nearly every inch of terrain TSR or WotC has ever produced into a massive, internally consistent megaverse. Problem is, I don't exactly think there is as much a market for this as you might think there is.
Comic Book crossovers generally work because they focus on characters and their stories. A comic crossover is great because it puts Spider-Man, Ironman, Wolverine, Deadpool, Mr Fantastic, Daredevil, and other heroes up against either impossible odds or invincible foes. The story is big because we follow those characters separately, and then enjoy watching them team up or clash.
D&D, for the most part, is different because it makes the player characters the focus and many games rarely even involve official D&D settings or characters. Sure, D&D has some famous names like Drizzt, Mordenkainen, or the Heroes of the Lance, but in general D&D isn't about big personalities. If there is any exception, it’s that certain villains from modules like Accerack and Strahd hold fond memories of players defeating them, but overall, D&D doesn't have the big names to support a decent crossover event. One need only look at the debate about adapting a famous D&D story (like Crystal Shard or Dragons of Autumn Twilight) into a big-budget movie to see that D&D doesn't have much consensus on what its own iconic moments are.
Moving on, most of the characters you mention are extremely obscure at this point: Nobody under 40 knows who Aleena is, and many current players might be hard-pressed to name Jozan, Mialee and Tordek. The D&D cartoon has a little punch due to nostalgia, but I don't think many people would even know who Strongheart or Warduke are. You might have some luck with the Baldur's Gate NPCs (esp in light of renewed interest due to the third game) and a little luck with the iconic novel heroes (Drizzt, Elminster, etc) but the era of "D&D having iconic recognizable heroes" is largely over. As I said, you would do moderately better with villains (Strahd, Soth, Tiamat, Asmoedus, Accerack, Xanathar) but unless the idea is to march around the universe slaying BBEG, I don't see much value in the League of Super Villains.
These days, you're "big crossover event" might be best done as some massive, interconnected streaming event crossing over Aquistions Inc with Critical Role, Dice Camera Action, the Waffle Crew, and other famous streamers all playing their iconic characters. There is far more love and respect for those characters in the community than there is for most of the names on your list. Plus, the opportunity to see streamers who don't always interact with each other would be far more interesting than name-dropping some obscure 80's character.
Mostly though, I think WotC has taken the right attitude with its slow-walk of various settings so as not overwhelm the game with settings and variants. We have Forgotten Realms as the default/kitchen sink, and have pulled back to reveal parts of Greyhawk (Saltmarsh) and Ravenloft (Barovia), along with fuller setting treatments in Eberron and Ravnica. (The latter opening a larger can of worms in terms of its inclusion; since it drags the entire MtG universe with it kicking and screaming). I'm sure we'll see Dark Sun or a fuller Planescape sooner rather than later, and continued nods toward Greyhawk, Dragonlance, or Mystara. Any sort of multiverse project cramming in Jakandor is bound to be a bigger headache than its worth.
So ultimately, such a project would be a big amount of work for a rather small niche market. I'm happy the implied multiverse (all D&D world more-or-less are reachable via magic, spelljamming or planar travel, even if settings like Ravnica or Eberron are more remote and have their own cosmologies) exists and I aside form the occasional nod or easter egg (like Mordenkainen in Curse of Strahd) I don't see much value in crossing settings in some universe spanning project.
Also, I read War of the Spark for MtG: keep Wizards away from the mega-crossover field if that's the best their writing team can do!