There must be a way to break this log-jam. I'm inclined to let go of the idea of canon, and just let this all become a series of "What if?" tales. There is justification for this. The first film set up a spectacular mystery of the unknown. One of the most appealing aspects was that the Alien was unknown. So much was left to the imagination in terms of filling in the blanks about where the alien came from, how it got there, what it was doing, etc. That is where the essence of bewilderment stems from, and in 1979 there could have been any one of a million valid answers to these questions.
Personally, I think Dark Horse is on the right track. They are showing, what if the story took a different direction at a certain nexus point. This isn't meant to invalidate any of the different sequels to Aliens, but rather to show how the story could have gone on a different tangent. The same could apply to the films. A sequel post-Aliens could take things in a different tangent without invalidating what went before. Maybe 20 years from now, someone else will do a different take that doesn't feature Hicks, Ripley or any of the other survivors but takes a different path. Likewise, this cold work in the other time direction. Ridley Scott's films could be set aside for a more bizarre Alien origin story based on actual elephant-nosed people. That would be interesting to many people.
In this way, new films recognize that it is all just fiction and pose the answer that, this is what could have happened, rather than saying that this is what definitely happened. This way, Alien 3 remains a valid tale of what could have happened, and other tales could be equally valid but different. If any new take turns out to be an audience hit, then maybe it will merit a sequel. Just at this point, I am all for seeing different spins as sequels or prequels to the two core films Alien, and Aliens. I would even be open to a comic that completely sidesteps Aliens as if it never happened. Why not? It's just a different approach to resolving a fictitious mystery.