1Q85?

I finished to read 1Q84 Book3. I was wondering whether Book4 would be published or not so I searched website and found interesting comment. Some people say, "Book3 describes from October to December, so if Haruki keeps writing the story, the title may be 1Q85 in Book4?" So some others say, "Probably, the Book4 would describe in the past. Book1 starts from April so Book4 would be from January to March but not after Book3 but before Book1." Well, we'll see.