We are nearing the closing point in the story they are taking on the top bosses now and getting closer to one piece but it’s still going to be a few years to solve everything.
In fact there is a lot of plot devices still in play.
There is going to be the reverly arc which is when a bunch of Kings and queens come together to hold a meeting with the world government.
There is going to be the black beards vs the revolutionary army
The all blue arc for sanji
Zoro vs Hawkeye.
And so on.
There is a lot of arcs still to come up.
I believe the reverly arc will be next and it might be a big one. It’s been hinted at for years and will bring back all of the royal family characters like vivi and King Neptune. There is also other story parts like that blind admiral who wants to get rid of the warlords and I believe dragon and sabo will show up to cause trouble.
If dragon does show up there is a good chance that we will get a back story on luffy like why dragon left and what happened to luffy mother.
Finally if he does show up more than likely it will lead to a war arc where all the kingdoms who luffy saved will ally with dragon and fight the world government.
So my point is it’s going to be a long time till we finish we are at the point where we are building up to the end but that is still going to be a long time.