I hope larian retcons the avernus ending in the epilogue where the hell gang (aka tav/durge, karlach and wyll) find a potential solution with the forge lead, and instead just add that storyline as a quest in act 3. It would probably be much more complicated to make a post-endgame avernus story dlc anyway, and we already have a ton of set pieces in act 3 to utilize.
For instance the gondians/Steel watch factory could give clues about the enriched infernal iron and its ties to an important forge in avernus, then helsik or raphael could give information on how to get to it. Hell, make it so you have to make a deal with raphael or pay a huge amount of money to helsik to get here. A contract with raphael could then just be broken by killing raphael in the House of hope questline anyway, because fuck that guy. Finally, lock this avernus forge- quest until you finish the gortash questline so that some key scenes with karlach are still played, just to add some exposition to her quest and make it flow better (that is, itd make sense for the gang to finally look into clues to helping karlach after her intense breakdown, plus that scene is too good to ever be changed/removed). The original avernus ending we have now could still be one of her potential endings if you never pursued her quest, so the new epilogue wouldnt have to have anything necessarily removed but instead one more ending added for karlach where the forge quest was already completed.
Im not a game dev so i might be pulling out of my ass with saying how this would be easier and preferable to accomplish than creating a dlc, but larian probably believes a dlc would need to have ton of new content in it to ''justify'' its existence, unless its a free dlc. Plus developing a post-endgame dlc must be super complicated with all the endings and other story flags thatd need to be accounted for, not to mention the level scaling being a problem - adding new levels from 13-16 for instance would be challenging for larian i imagine, but being locked to level 12 would suck for the players. An updated questline for karlach in a future patch or definitie edition etc wouldnt have to be as substantial, adding maybe about 1-2 hours of new playable content and maybe a thousand or couple thousands of new lines (i contrast, i believe the new epilogue update we got in december added +3000 new voicelines). Still a lot of work, no denying that, but not comparable to how much work a dlc project would need.
Anyway, just speculating ideas lol. Despite the new epiloge adding more hope and hinting towards the idea of an avernus dlc, i think itd be an unnecessaribly large project for larian to work on when act 3 aleady has a lot of great leads and set pieces that'd make sense to use for a karlach questline, saving larian time and money on having to add tons of new characters and story exposition in a post-endgame dlc. That being said im not opposed to a dlc by any means, nor is there any confirmation if larian will ever pursue anything like this, but only time will tell i guess.
