If he finishes it in 100 chapters or less (aka 3 years) it will be bullshit by default.
Oda himself brought that upon him by spending countless chapters on completely redundant stuff.
People would rightfully be pissed that he dragged out way less important setup arcs seemingly for ages and then squeezes the actually important stuff of the series (well, ALL the important stuff and mysteries to be exact) into a speedrun session that is shorter than Dressrosa or the raid on Onigashima - a mere act of the Wano arc.
What kind of good story has 90%+ buildup and less than 10% actually important reveals/resolution etc.?
Sadly, people will still appreciate and defend it citing Oda's bad health or some other BS.
One Piece has been garbage since time skip.
The problem is, we know Oda can write, draw and deliver, but he dont. He chose an easy way out, he didnt even try to keep his promises and kept on adding layers without unfolding any special mystery.
Have you read about his recent interview with Detective Conan's mangaka? He said he wants to bring back Tom and Jerry type stuff to manga because that type of art is going extinct.
Do we need to remind him that Tom and Jerry movies are still being released?
I have just one word for this man; Shameless.