I believe either the patents have expired or the basic functionality was always royalty-free; but what really killed JPEG2000 was the immense complexity and increased processing power required. It still has applications in some niche areas, and probably most people's contact with it will be in the form of images embedded in PDFs (many of archive.org's ebooks use JPEG2000), where the noticeably slower rendering of pages is a big turn-off.
