I'm sorry to be the forever hated pessimist here, but if never making another warriors book again is what she (or a group of she's) wants to do, then why are you hindering their wishes? If you just
adore her/them so much, don't you want them to be happy? It was eventually going to end, so why are you so worked up that it's ending now?
their are a bunch of potterheads out their! but she kept writing!
Actually she kept it at seven books though there were people
dying for more, but you don't see all the Harry Potter fans foaming at the mouth trying to make her write more. As well as a wildly popular trilogy,
The Hunger Games was also kept at three books, even though there were fans demanding more.
Jeez, you don't own the lady(s) so just let her/them do what she wants.