I gave up on this show just a few seasons in when I realized the showrunners/writers had no plan. What I like about cable/nontraditional (Netflix, Amazon) TV series versus broadcast network TV shows is that the former generally have an outline going in: there will be a beginning, a middle, and an end, and everything will be wrapped up in just a few short seasons. Whereas with broadcast shows they'll try to keep it going for nine or ten years or more, generally long after the quality has gone and many of the original actors have left for other projects.

AMC, unfortunately, despite being a midlevel cable network, decided to go the traditional broadcast TV route: as in, let's beat the hell out of this show until every last drop of advertising profit has been squeezed from it.

That said, since the zombies in this show (like in most contemporary zombie shows/movies) are not actually the "undead", but are the victims of an infection, the show should be ended in a similar way to the film 28 Days Later (I am disregarding the sequel):

Since there are very few "normal" people left, the zombies' food supply is running out, and the zombies can't reproduce, so the zombies should gradually die out on their own, and the surviving humans should go on to a new beginning on a mostly depopulated Earth.

They should've been able to do all of this in three to six seasons, rather than nine or more.

Good question. The show apparently has been mostly following the comic book story (which I have not been reading). I don't know how closely they have been following it nor where the comic book has been taking the story. I agree that the show has become a bit too formulaic. The group always runs into a dangerous rival group and fights them for a season or two. They make the same stupid mistakes. This last couple of years with Negan became almost laughable. They cycled between showing Negan being Negan, showing Rick and company swearing they would kill him, and then wasting each opportunity they had to kill him. Usually they just told him how much they hated him and planned to kill him, wasting time talking instead of shooting him, until the opportunity was lost. Darn, he escaped justice again!

I am guessing that if they want to end the show (which will probably depend on how the ratings continue to go) they will look for some kind of happy ending of some sort.
But this show has gone on a long time and has had a fair amount of success for a non major network show. I bet they will leave open the possibility of bringing the show back at some point, at least for a short run. It wouldn't be hard to do, even if a "cure" is found. They can always write in a new outbreak of some sort.

Here is a question; will Rick be killed off in the final season, in the final episode? That would just about rule out him showing up in a sequel. Will Rick become a walker? He could be cured later on if a cure is found.

We are assuming that Rick will be killed off, but the writers may fool us so he can show up for the show finale.

Yeah, I was wondering if they will kill him off in the series finale. That would pretty much rule out him showing up in a sequel of course.

I meant he will be gone next season but might show up in season 10 for the SHOE finale.

For me, after everything this group has gone through, there is only one way this show can end: in peace, a happy/hopeful ending. I don't know if the writers would dare deprive the fans of that. Some fans might not stand for anything else. I just hope they don't leave it open ended with some damn tag line like, "The fight against zombies will continue" then fade to black as our group is surrounded by zombies.

Yeah I think they ought to end the series with a cure or some kind of happy ending like that. If they ever decided to revive the show they could easily write in a new outbreak somehow. So a happy ending would not rule out some eventual revival of the show.

Maybe they could find some island where the people had a vaccine so that once you're dead, you're dead. Then they could live there in total peace, provided they could get along with all the other humans. lol