Stone is a tad tricky, but I don't see see it going that much longer given its current pacing. I'd imagine by the end of the publication year the current arc will be done, and after that there's relatively little left to do beyond moving into a final arc. How long the final arc + epilogue would exactly be is again speculative, but the series pacing is such that I hardly imagine it being that long.
For reference, I wouldn't be surprised if the roster come the latter half of 2020 looks like this:
-One Piece
-Haikyu
-My Hero Academia
-Black Clover
-Act-Age
-Jujutsu Kaisen
-Chainsaw Man
-Samurai 8
-Mission: Yozakura Family
-New Series from Masaoki Shindo
-Fantasies by Ohsuga Gen
-New Romance Manga by Tsunehiro Date
-Sci-Fi series from Takamasa Moue
-New series from Random Author
-Fodder
-Fodder
-Fodder
-Fodder
-Fodder
-Gag Manga for the Kids.
Obviously a lot of this is speculative (and Yozakura is borderline indulgence on my part), but that's my take on things.
TPN and KNY i can for sure gonna end both in similair times. kny can extend its life-span but i dont see it happening from the writer, TPN prob gonna end early next year
mha seems to be the replacement for one piece when it ends. i can see it last till vol 58
haikyuu, i think they gonna win the tournament. after this much climax, it would be a waste to throw it away. like it wouldnt make much sense to start over again.
romcoms are always random, and idgaf. they are just here for diversity
JJK can go very long, similair as bleach
Drstone did you all forget about the premise?, senku is gonna revive civilization.. thats something that always has to do with alot of pacing. btw we finally got an arc OUTSIDE the ishigami village, do you guys read the manga clearly??. it can go for 10 years if it wants
chainsawman is really unknown, it depends how long new interesting characters come and go
Black clover depends how people still view the manga, rather than something thats being pushed. if there is an new genius mangaka's doing masterpiece battle shonen like hxh, people gonna get tired of bc if it keeps getting ''anti-climatic''.