Often there is no way to determine this before the bluebook comes out during the summer. However, if you’re hoping to take a specific course, it would be a very good idea to contact the professor that usually teaches that course ASAP, to find out if they intend to teach it again, or whether they will be on sabbatical, etc. (They may have a firm sense of what they’ll teach next year long before the official list appears.) Also, note that many seminars closely track faculty interests from year to year, and that many professors teach a particular seminar only once! So, if you have specific seminars on your plan for depth courses, it would be a good idea to check each year with your favorite professors to see what they’re planning to teach.