New Diablo game - Expansion, but not what we might expect

Hey there.
Here is the second part of the new diablo game post series. There will be three in total,
So why is the new Diablo game an expansion? Why not a spinoff?
Well lately blizzard moved towards making e-sports. Besides Diablo, all of their games were created for this reason. Even wow to a degree, but Star Craft II, Heroes of the Storm and Hearthstone are definitely designed for competitive play. Overwatch will be no exception. This is important because Blizzard probably won't make a new game at this point that can't be turned into an E-sport. Additionally, they are probably smart enough to create competition to their own games, so no second MMO or RTS or card game or MOBA. That leaves precious little room for a diablo spinoff. All that's left is a fighting game or a rhythm game, and neither of those choices say diablo to me.

As good old Sherlock said: "When you have eliminated the impossible, whatever remains, however improbable, must be the truth." So the truth is, we get an expansion.
The game seems to be hinting at a likely storyline. Diablo is back in business and Imperius is on a collision course with the Nephalem. Fun fact: nephalem has no plural form so as far as the cutscenes are concerned there can be any number of heroes playing.
But back to Imperius and Diablo. I'm not buying it. One problem is that we are just too damned powerful for them posing any kind of challenge,

Imperius Angel of massive jerkassness is hyped as being an ultra badass, but Diablo wiped the floor with him. After that we killed Diablo like it's an everyday business to us.
Malthael was the head of the Angiris Council. As the aspect of death he boosted his considerable power with each death his friends caused. And he caused about as much death as Vlad Tepes, Genghis Khan and Hitler combined. Halfway into the fight he absorbed the black soulstone and all seven evil with it. Meaning, he added all the power Diablo posessed in the previous act.
So, how are these two clowns supposed to pose a credible threat to us? They can't.

At best Imperius and Diablo could work as smaller bosses like Leoric, Maghda or Adria.
Additionally there is the fact that we already had an act set in heaven and another after that spent with killing a  bunch of angels. So an act VI dealing with us going to heaven to kill another Angiris Council member would be a terrible rehash. Blizzard is better than this, Also you can't make Diablo an act boss twice in the same game.

So if not this, what will the expansion be about? Well I can't tell you that as I am not in the development team. I just wish.
But I can tell what I think it will be about...
Right after I get some sleep.
Evil I know.
Good night everyone