I would be extremely surprised if they added in Avernus. I suspect that was something which was cut early own before they actually built any maps or content for it.
I also think the Act 3 witch coven content simply got changed to having Ethel as a recurring character. I suspect this was originally going to be a sea hag lair before they changed rather than cut content.
I believe the Minthara content is actually just bugged and will be fixed with a patch. Hopefully the same can be said about all the epilogue stuff as there’s plenty of recorded dialogue for it.
That said by the sounds of it the Upper City was probably cut late in development and does affect the pacing of Act 3. I hope a definitive edition does give Orin and Gortash more time to do their things culminating in bigger battles and better pacing.
