I can see how some people would want a multiverse, but to me, it feels a bit lazy on the writer's part.
"Something makes no sense? It happened in a different reality."
I don't know, it feels like we suddenly put time travel in this franchise, time travel works great in Terminator, but I can't see it working with Alien and Predator. Similar with how multiple dimensions works well with Star Trek, it doesn't seem to fit with a grounded and harder sci fi that is this one.
Just like Hicks said, they should just try to fix continuity errors rather than just wipe them out. They did the right thing with the name changes in the old novels to incorporate Alien 3. (Quick question about A3 since I hear this whole "teleporting egg" scene, do we actually see an egg on the Sulaco? Or is it just a Facehugger?)
And Ultramorph, I agree that it benefits Godzilla well, but that's because Toho doesn't seem to be sure in which direction to take their franchise, the Showa era is a great example of him being a kid friendly hero in one film then a destructive anti-hero in another to a full blown villain in the next one.
Another cause for concern about retconing is look at how it affected Star Wars, a lot of people got upset that a huge portion of their favourite stories are now redundant thanks to the new Disney canon.
I'd rather they simply say "we won't be mentioning old stories, they happened in the past. This is a new and refreshing start", like look at Rage War, it's set centuries after Resurrection, so it's a new chapter and it would be pretty hard to contradict previous stuff as it's centuries later.
I think Predators had the right idea by simply ignoring everything and just mentioning Predator, it didn't feel like a separate universe, heck, the Predator changes visions, where else do they change visions? Predator 2 and AvP (the foot print vision is used as well)
Keeping things in a single universe and adding to it enriches it more for me, and a multiverse takes away from that enrichment.
But if they do officially confirm a Multiverse, then oh well. I'll try to find some ways to put it all back in one universe in my headcanon.