This would be a perfect final arc for warriors imo
This includes spoilers for POT, OOTS, Crowfeather's Trial, and ASC, but the most of them are really minor spoilers, and they are all covered, so do not worry.
There is a time since I am thinking the new arcs are losing the quality and that there needs to be a change that will bring a complete unexpected arc. An arc that will bring surprises and big differences. Something really new.
I guess Warrior Cats should end (at least in making new arcs, maybe they can go on with supereditions and novellas) because after so many series and years of making more books, it changed da lot and unfortunately will never come back to be what it was once - the much beloved first arc, that in my opinion was the second better arc not only for the nostalgic feeling it gives me, but also for its simplicity that makes it somehow above the new arcs that includes magic things happening and going a lot away from the reality.
But, I still think before it ended, there should be a last arc, the 10th, the complete arc, the arc of farewell, an arc that will have to bring with it changes. And with changes I mean a lot of unfortunate events that will explode the chaos in a way never happened before. Yes, basically a crazy arc, also trying to put finally right some things the fandom does not like in the new arcs.
For being more specific and explaining this further, I think the arc I wanted they made was like this: we should follow the POV of a medicine cat mainly. A medicine cat that will have a breakdown just like >!Hollyleaf!<. I also think they should bring every kind of unfortunate event we already had in a bunch of worrying for the Clans more interesting than that stupid prophecy about >!SkyClan.!< And with this I mean, instead of foxes and badgers,maybe new aggresive animals, maybe intruding cats attacking too, >!those animals that attacked in Crowfeather's Trial!<(I just forgot the name lol), climatic changes, and the main one: scarce food and solid fights and chaos between the Clans. Also bring a prophecy that actually makes sense, without StarClan speaking in code just like always, and useful tips. Bring such a worry that will make it actually look like the Clans will end. I am full of seeing these stupid prophecies stirring everyone up when the situations are actually not so big. Such unfortunate events that will kill all of those NPCs that stand in the Clans with no personality, so we can focus on less characters and this way having more solid and unique personalities and not only clones. Let only the most mentioned and important characters alive by the end.
Also kill >!Squirrelstar!<, and this is not biased because I hate her, but because it would be the death of an hero by the end like a tragical final event just like>! Firestar's death would have been in The Last Hope. !<Just make it a complete unique story for the end of this series, because it should already have ended. With new morally grey characters, also because this fandom loves them, and characters being properly developing (better because we would have killed all the NPCs). It would be a crisis arc. And of course, a villain. I have poor ideas of new kind of villains because it looks like they have already used the most interesting ones, but it could be the own protagonist medicine cat. We need villain medicine cats, right? And just imagine the POV of a female medicine cat villain in an arc? Female would be the best option because we need more female villains. This would be different from anything else in warriors. Bring good motivations for a well developed and slow transition from hero to a villain and also it would be interesting if she also tried to fake being a good cat while secretly kills cats in the medicine den or anything like that. And develop this well, with the second half not being completely different from the first like A Vision of Shadows but actually bringing every moment with a consequence in the future.
Do you see how many changes and surprises it would have? It should end Warrior Cats with exact 10 arcs and just stop it because this stupid cats' books is taking out all my money. I know it is almost impossible they bring this, I am just saying it would be pretty cool and it would be a good end for Warriors with such a crisis. Would you like this kind of arc?