It’s pretty clear — as Mike said — the band is focused on the future. They introduced the new lineup a few months after Papercuts release that got almost no promotion or interviews. Papercuts still had the old lineup listed and promoted. Then came "Sep 5," which I think pretty much closed the Chester era, at least for now. I don’t expect another anniversary box soon; they’re treating this as a fresh, updated era. They’ll probably put out a live release and then work on the next studio album.
I also agree the band doesn’t want to dwell on the Chester era anymore, even if that sounds a bit harsh. There are signs: no Chester vocals in LPTV episodes, very few tributes during shows, using re-recorded Emily backing vocals live, etc. Papercuts really felt like a closure to that chapter.