The only silver lining and consolation to be had here would be this.
The original alien film is basically perfect, and it always will be. The second film was the ideal sequel, and basically did Aliens as an action movie perfectly. And we got the queen, the hive, the colonial marines, and other awesome stuff that has lead to some great novels and games (ACM excluded). It built the rest of the world for us. This alone would probably be enough. But If you're like me, Alien 3 was fantastic and a satisfying end to the original trilogy and the Ripley arc. So there's that.
Resurrection was our "fun take" on the Alien movies. Alittle something different for those who may have wanted it. The first two predator films were fantastic. Predators 2010 was an enjoyable enough romp and took itself seriously, I wouldn't say it was garbage. The Alien prequels have basically been wrapped up well enough at the end of Covenant, with David having created the xenomorph and escaping. He has his freedom, we know where the xeno's came from, we know what the space jockeys are, and we know enough about David's plans and motivations to walk away if we have to. And we're about to get a goofy take on the predator franchise. Kind of a predator version of Resurrection if you ask me. So that's covered.
So aside from never getting a proper AVP movie, it's really not the worst place for it all to end. We've basically had a taste of everything, except (like I said) a good AVP. But there's two of them to watch if anyone ever wants to.
I doubt Hollywood could or would ever truly kill the franchises. They may get lost in limbo for God knows how long. Maybe 20 years. But I think that, given enough time, a lot of patience, wheeling and dealing, and a long break from these films will make somebody want to sell them, and someone else want to bring them back. I don't think we'll ever see the day when they're actually gone forever, but we may be in for one hell of a long wait.
But as long as those original movies are around, we'll always have perfection.