The ultimate punishment, after everything he destroyed and sacrificed Sargeras returns as what he thought out to destroy.
Imagine Sargeras returning as a being of Fel & Void. This would be a cool way to bring him back without the “Burning Legion Theme” burnout by throwing in some Void.
Additionally, with the return of Sargeras, Illidan may begin to train new Demon Hunters, opening up the class to other races in the game.
Let’s not and say we did.
Because… that worked out so well last time?
Void and Fel are not direct opposites like Light and Void, but because both are destructive energies they still are incompatible in proximation.
I previously thought it would be interesting if, in the absence of Sargeras, the Legion turned to the Void for power. Void Imps, Void Eredar, etc.
Sargeras comes back a la Dragon Ball Super Frieza and we judo kick old Zovaal in the booty
I don’t know if I’d really do that. Fire mode Sargeras is extremely iconic on who he is. An additional void corruption seems unnecessary. He’s already pretty cool and intimidating as a villain.
And if it’s just to give an excuse for more dh races then no, it’s not worth messing up Sargeras for that. 
Plot twist, SL follows the end of Thor: Ragnarok and Sargeras the giant burning Deus ex Machina brings his sword down on the Jailer and Zerith Mortis. Also solving the sword in the planet fiasco from two expansions back.
Yeah we can have the void Legun instead
Sounds super boring. Ready to fight some forces that are not Void/Fel/Death aligned.
If Sargeras is going to get any sort of “transformation”, he should use Illidan as his avatar and be augmented with that “Sargeras Gul’dan” look, those hulking spires of horns and the golden flames constantly erupting. Making him Void defeats the point.
Honestly I’d like a way to just bring Sargeras back in general. He was supposed to be the “big bad” of the Warcraft universe, only to be yeeted away by the Pantheon and replaced by the Jailer, who is extremely underwhelming.
Yes, it worked, he would open the portals the Gul’dan wanted. It exploded because it overloaded both energies, not because it mixed them.
Zovaal sucks. It’s such a shame because this expansion has some good, fun villains like Muehzuela, Sire D, Devos. Zovaal is just such a big nothing-burger. They tried to mystery-box him and it is backfiring so hard in my opinion.
^
Let’s do that one
Got some bad news for you.
The void, the fel and death are all intertwined, related to (directly or indirectly) to one another in some way shape or form.
So odds are, as has largely been the case throughout the entirety of the game and the lore, any one of those three things or combination of said 3 things are going to be present in same way shape or form.
Enjoy
He’s one of the big bads. There are plenty of others who also matter. But I’m pretty sure that’s why they went the jail route. It’d have been a total waste to fight or kill him Legion and there’s no believable way we could even hurt him right now. Sargeras is still no contest the strongest being we’ve ever met.
Jailing him is keeping him in the cards for later in the future, but getting him out of the way for the moment. I guarantee we’ll see Sargeras at some other point eventually.
We totally could have had a scuffle. We fought Vergil three times in Devil May Cry 3 and each fight was better than the previous 
And yet, the writers will find something bigger and badder. Zovaal, the first ones, the one above all, he who remains, and then mega dreadlord Jaina
I read “Let’s retcon an entire expansion so we can add more DH races” and laughed pretty hard.
I don’t care if they are ‘present’. Death Knights, Warlocks, and Shadow Priests are ‘present’, that’s fine. I’d just like to rofl-stomp the forces of Light, Life, and Order for a change. And don’t pretend that’s impossible because those are all good aligned forces or something ridiculous like that - we’ve fought the Scarlet Crusade, Druids of the flame and nightmare, and any number of Titan constructs.
We could stand to have an expansion where the big bad had nothing to do with the more obviously nefarious forces.