The trade paperback will be available in the UK in three days. (At last!) It's the ebook that comes out in December.
Even though amazon.ca is still listing the mass market for pre-order (so embarrassing if they have to give people back their money) it's gone from amazon.com so I guess it really was somebody's mistake.
If the other editions did fabulously well, I suppose there could be a mass market paperback in about a year, but no guarantee even then.
The book was "orphaned," which is what they call it when the editor leaves the company for a job elsewhere. And what that usually means is that no one there at the publishing house cares very much what happens to the book. There is no one to advocate for it in terms of publicity, future editions, etc. I've had books orphaned before (I seem to be the poster child for orphaned books) but there was always someone left who was invested in the book in some way, so it worked out much better than these things usually do. This time it doesn't look like I am going to be so lucky. Probably everyone who was there when the book was published the first time is long gone.
Edit -- Sunday
And now just to show how fickle they can be (although in a good way), it appears the book is in stock now at amazon.co.uk