~4-7 chapters.
Just think about it:
- Road Poneglyph still is missing/hidden
- Big Party hasn't happened yet and Jinbe/Yamato officially haven't joined.
- Plot thread closure for many characters (Kin seeing his wife, Drake explaining his goals, Law and Kid's next goals, Apoo/Hawkins' fate) everyone saying goodbye to the crew.
- An admiral is coming and it needs to be addressed (whatever it is).
- The smile fruit/Ebisu curse being cured.
These are things that NEED to happen. Not to mention important things like Zoro visiting Ryuma's grave/his lineage/Nidai potentially being addressed, the Poneglyphs in Onigashima and the Capital castle, etc.
It cannot end next chapter lol