Thinking some stuff:
-Neverland is clearly going to be the next Jump manga to end. In 3 chapters?
-Yuuna-san would be the next one. But it has started a volume or was ending a volume, so is getting at least 8 chapters. Still, is Yuuna-san, so we can expect it to somehow still lasting.
-Then it would be Haikyuu. Current game has lasted 13 chapters so far. I expect it to end in 15-20 chapters. The big question is: will Haikyuu end after this game, or will it get more games coming?
-Then We Never Learn. Each route is lasting 8-9 chapters, so I calculate 25-30 chapters left.
I see two things:
-2021 is going to be a curious year, with Jump being composed by One Piece, My Hero Academia, Black Clover, Dr.Stone, Act-age, Jujutsu Kaisen, Chainsawman, and 13 2020 not-consolidated newbies. I can't still imagine Act-age being the 5th oldest Jump manga in the roster.
-It seems there is a 7 issues gap between my estimation of Neverland, Yuuna, Haikyuu, and WNL endings. If I'm right (I'm not sure about what I've posted btw because who knows what will happen), then are we getting a veteran ending before every new serialization round for a while?