Out of curiosity, since Diablo 3 is now on the Switch, I wouldn't mind seeing any Blizzard content later as DLC in terms of a new character, stage, ATs, even music. Granted its impractical for a Blizzard character to be in Smash because the roster as we see it are fan-favorite picks from the ballot, but its not entirely impossible. Doesn't mean it'll happen in any regard, but there are plenty of iconic franchises left to represent imo. I'm not entirely a die-hard Blizzard fan, so I may have trouble with some of the choices I'd see work.
I'm only doing characters & assist trophies for now :
Fighters: Tracer- granted I chose her as an assist trophy a long pages back (those who've seen it would know), but I thought, you know what, why not bump her up to a playable status.
Overwatch is one of Blizzard's most iconic franchises, right up there with War/StarCraft series. Its aesthetic vibe perfectly fits Smash Bros for its wide spread of color that brings characters to life and the community is still going strong as of late.
In other words, I'd say her design & personality really fits Smash in my book. I won't cover up all of her movesets, but her's could be her dual pulse pistols, her "Blink" teleportation, Recall and her Pulse Bomb as her Final Smash. If I were to push myself for more (though one would be enough) would be Widowmaker. She's sort of the big arch enemy of Tracer, hence the few shorts that featured both of them.
(Fun Fact: did you know in Overwatch, that special ability meter when it is all charged up, and that character unleashes their abilities, yeah, kinda like what Smash Bros does when the character gets the Final Smash, they perform a special ability, its spelled with a U.)
Assist Trophies: I only have two (technically 4) in mind:
Winston from Overwatch
Eric, Baelog, & Olaf from the Lost Vikings.
What I can see Winston as an assist is that he can roam around the stage attacking the opponents, utilizing his powers such as his jump pack & the Barrier Projector, but when he gets attacked, he unleashes his "Primal Rage" ability and becomes much stronger with his attacks doing massive damage towards the opponent or more (Upwards to possibly 60% damage).
For the Lost Vikings, I believe are a lot more complicated to implement, but I'll make it short & sweet. Each viking has a different ability, Olaf is the defense, Baelog is the brute strength that gets in anyone's way, and Eric is more ranged thanks to his slingshot. One that gets knocked out means all of them are out as well (because balance is key).
Anyone like to share? or just keep talking about these arbitrary leaks all day...