First of all: What's that about a pattern? I know it was "explained", but in reality it looks like this:
Act I; 909-924: 16 chapters (not 15)
Act II; 925-955: 31 chapters (not 30)
Act III so far; 958-1017: 60 chapters (already, not next chapter)
That's not really a pattern. It is close to one, but the fact that it won't be exactly 15-30-60-30-15 stands nonetheless. So I wouldn't be surprised if the act goes for 10 or more chapters - it wouldn't break the pattern because like I said, there is no pattern.
Also, Nekomamushi vs Perospero still needs to be set up, Denjiro, Kawamatsu and Izo have practically nothing to do at the moment, which needs to change imo, there's still the mystery of the person who helped the Scabbards after their fight with Kaido, Orochi should still be alive, we need to see a bit more of Yamato vs Kaido and it kind of seems weird if Sasaki, Who's Who and Black Maria aren't defeated in the same act as Page One and Ulti. Not to forget Fukurokuju and Hawkins who are also currently fighting.
There's still much to do. I personally think 60 more chapters seems fair and that's only if everything goes smoothly. Meaning Onigashima doesn't reach the Flower Capital and the Big Mom Pirates stay away from the war. Otherwise I'd go for at least 80 chapters.
So end of 2022 is the earliest point I see Wano ending in and mid 2023 the latest.