Going forward, TextWrangler will not be updated for the next version of macOS, but it will continue to be functional so long as the new version of macOS doesn't introduce any software-breaking bugs.
Bare Bones is instead recommending its customers download BBEdit 11.6, which was released in July. Customers can use BBEdit 11.6 unlicensed indefinitely, and the unlicensed version contains the same features that are available in TextWrangler. BBEdit is not available through the Mac App Store like TextWrangler, but can be downloaded from the Bare Bones Software website.
What you may not know is that last July, we released BBEdit 11.6. You can use this version unlicensed, forever, for free. Without a license, BBEdit now includes all of the features that TextWrangler offers, plus quite a few others. That's right. You no longer have to pick between them.
BBEdit is free for 30 days, after which a license costs $49.99. Customers who don't wish to purchase a license can continue to use the software's free features indefinitely.