I'm guessing when they get to 11 (Spinal Tap reference?) they might think it's time to pump out a new edition. Or they just don't go there and stop printing, end of the book's run.
And just as a general point, Wiley's modifying of the book on different printing (not editions) is a little out of the ordinary. The idea of a printing is exactly that: you print more of the original book, using the same printing plates, etc.. A new edition is supposed to be an updated version of the book where one would add new information, changes, updates, etc.. Wiley is mixing the two things and it's very confusing. Ad that they refuse to admit they're making the changes and won't publish an Errata sheet (and it would be very simple to do so online) and you have a really crappy process for finding out what's been updated.
So with that info, as each new "printing" is in fact a new "edition" and there's no record of what has or hasn't been changed in which printing, we just have to rely on people finding issues and posting about them online. In other words, what Wiley should be doing but won't which is quite frustrating. They go to the bother of changing the book itself on each new printing but don't think it's useful to note what these changes are on a webpage. The reason for this lack of easily located official Errata can only be guessed at. And my own guesses don't do Wiley any favours. They are, it seems, like the MacDonalds or Walmart of publishing: they're huge, they're everywhere but they're not very good. And you can't really avoid them.