Copies may still be available at physical bookstores, until their stocks run out. Used copies are for sale on Amazon and other websites. But as of right now, it doesn't look like there will be new stock coming in.
If you are looking for a copy of the book, there are still options available. The E-book is still available, and will not be discontinued. Audible has an audiobook version that will continue to be sold via their website.
We will let you know if there are any updates.