User blog comment:Xilinoc/Ch. 683 - The Dark Side of Two World Ends/@comment-4080775-20160727005940/@comment-4080775-20160728000308

You might say that, but it is still possible. Just because he can see all futures doesn't mean he can't be fooled, or those futures are real. Aizen already messed with Yhwach's perception of time when he was visited before, and based off Yhwach's response, he never saw that coming in any future. It's entirely possible that Yhwach saw Aizen's Shikai 1000 years ago and has been under its influence ever since.

Anyway, hopefully we will know what's really going on in the next chapter.