I'm under the impression that regardless if KFP4 being a good film or not, it is certainly promised to be a divisive film depending on where it goes.
Like, you have posts ranging from implied redemption arcs, disappointments of characters not being involved, and maybe the one or two hate-post on a character not given a chance yet. (You know who you are). Well here's my take: I believe KFP4 will be fine for what it is. I'm prepared to give the new characters a chance, even a certain one I feel is the most divisive of the bunch, I'll like the movie for what it is vs. on what it couldn't be.
I consider myself a very easygoing KFP Fan. Heck, I defended LOA once upon a time. The closest I ever came to be critical to KFP related content is basically late Dragon Knight Season 2 and the rather personally infamous plot-twist for the series' endgame, but that's unrelated and more of a personal gripe on my end as is.
Being clear, I'm not ignorant to concerns of this ending up being the Dreamworks Equivalent to Toy Story 4, and fine enough, I used to be cautious of it catching Unnecessary Sequalitis myself, but from what I saw in the trailer, it's thus far still KFP.
And end of the day, that works for me.