I voted "No," but as with everything else, there are various degrees to which this is true. I'm definitely all in on separate Alien and Predator canons, but I'm also flexible within those separate timelines as well.
I've made it very clear on the boards just how much I love Alien: Covenant, but that being said, I don't really ever find myself thinking about that movie specifically when I watch Alien. I do like seeing (and talking about) them existing on the same timeline, but in the moment when I'm actually watching them, that's not what really matters to me. And while I wasn't really feeling Blomkamp's idea just because I don't think that what we were seeing from it looked very good, I wasn't overly precious about the ramifications it would have had on the canon/lore. I love Alien 3 and I don't want to see it bumped from a (the?) continuity, but the movie will always exist; it'll always be there. If there's going to be a split timeline that goes in a different direction after Aliens, I'll still always have Alien 3 and I'd admittedly be curious to see what someone else does with an alternative idea.
Predator, I'm even looser with, if only because the movies themselves are all, functionally, standalone films. There's little bits of connective tissue, yeah, but there's no reason why you shouldn't just be able to pick any Predator movie at random out of a pile, put it on, and (quality of the overall movie permitting, of course) have a good time with it as its own thing.
As for AVP, I've never been one that's really cared for it conceptually (probably because my main experience with the crossover is from the movies, which I find to A.) be bad in their own right, and B.) I don't like their silly attempts to merge a full-fledged continuity between the Alien and Predator movies that existed at the time with their Weyland and Yutani shenanigans). That being said, over the last year or so (since Prey's release, pretty much) I've come to accept that we will eventually see another stab at an AVP film, probably sooner rather than later, and I've started to really soften on the idea, provided it does something more interesting with the material that it has to play with than the two movies we've gotten. Though I'd still prefer it to be totally outside of the Alien movies' canon, if at all possible.
And then there's the EU. There's some pieces I really love (Alien: Isolation, The Cold Forge, Into Charybdis, Phalanx, Inhuman Condition, Sacrifice, Salvation, Dead Orbit, etc.), but with the POSSIBLE exception of Isolation, I tend to see the EU as something separate from the universe of the films, if only because the films have proven time and time again that they take no issue with walking all over the games/books/comics, and because if they are fully separate, then that would allow the EU material to have the freedom to really experiment and try new things that would never work on screen and just have fun with it. A lot of the older Dark Horse comics feel like that. Hell, Alien: Resurrection feels like that, despite being a movie we actually got on screen.
I don't think Alien and/or Predator should go the way of, say, the Halloween franchise with numerous hard restarts every few years that try to shift the public's perception of the franchise and make you forget what's come before, but I don't mind the idea of the canon being something more akin to the Godzilla or James Bond franchises where continuity can take a back seat in favor of the individual entry's intent (either within the tapestry of a larger universe or as a total standalone, varying entry to entry) taking priority.
