I don't think we are even after current arc as there still many mysterious ahead for the series, I rather not it end early even on Webcomic and like One and Murata keep going as long they have ideas forward with that. It won't be like DBZ as unlike it, it actually make side and minor characters grow strong and be relevant even later and have better written on how to handle everything with OP characters, power-scaling, and so on. I like OPM get their dues for what it is and like it to expand even eventuality it ends.
I think we are probably over half-way through ONE’s story now. Not to compare but Mob Psycho was pretty short webcomic, we can possibly expect the same though OPM is ONE’s love child.
it’ll probably be 2/3 more arcs after this I would like to see:
- Neo Heroes Arc (ft. The head of the Organization as the final villain and his links to the neo heroes and hero association, some twists/info on Bofoi/metal knight and Genos’ Evil Cyborg villain)
- The reason why monsters are increasing rapidly, return of Garou as an ally, the collapse of the Heroes and rise of monsters Blast shows and loses also (everyone discovering who Saitama is the introduction of God)
- Saitama finally loses once to this God entity and actually increases his skill level/techniques or martial arts to match the god like threat.
END
I think that’ll cover virtually all of the mysterious things left if you include background on God, Saitama, the shady people. Why mysterious beings even exist and why people have limiters and why heroes come about. Or just leave it hanging idk, if ONEs writing of Mob Psycho is something to go by its slightly worrying. I may be in the minority here but I detested the ending of that series. I don’t wanna be let down.