I have noticed that all of the screenshots and trailer for HW2 feature only brutes as the covenant. Any ideas if we will see any elites?
I wouldn’t see why not. I would assume they are using ALL of the Covenant in some shape or form.
Maybe separate Brute and Elite factions?
We know for a fact that Sangheili will be present in the multiplayer, but the for the campaign we still don’t know.
There are a couple seen driving ghosts in those screenshots and one on foot.
I imagine this is a combined Covenant like in Spartan Assault, maybe because of the distance they were out of the loop (or convenience, or the fact they are Regrets troops).
You should check Halocannon’s video about the Halo Wars 2 screenshots.
In the pictures he showed there were some Elites.
There were;
- An elite Honor Guard - A elite controlled Ghost - Two elites with rifles They all used the Halo 2 Anniversary armor, but I have no idea to what kind of Covenant faction they belong, guess we will find out soon enough!
Yeah their will be eliets and yes they show their original armor designs!!! 
. It’s most likely multilayer only. But I imagine Spirit of Fire will get some kind if UNSC back up. Spirt of fire being back up on coms will surely draw attention from UNSC can’t wait to see how the scene will pay out! Possibly swords of sangillios/ UNSC aid?
Read that Halo wars 2 is post halo 5.
It’s most likely confirmed since we see them in screenshots Will they be in the Campaign? Maybe, doubtfully. Multiplayer? Sure, most likely.
Multiplayer, Yes. Campaign, Probably, like 85% chance I would say.