All of Part I and sections 10-15 of Part II are deployed ubiquitously in most of the world today. As is section 22 of Part III (WireGuard, WPA3, TLS, etc. use AKEs).
The rest of it appears to consist of "areas that theoretical cryptographers are refining in preparation for real world use". This is the stuff that will be deployed in the real world come 2030.
So, to answer your question: More than half of it is actually used today, and at least 80% of it will be used soon. If you're going to take a course in this, it's better to be ahead of the curve than behind it. (Otherwise, we'll all be suffering through textbook RSA ad nauseum.)
There's a conference going on right now at Columbia University in New York called Real World Cryptography if you're interested in seeing what the state-of-the-art looks like for real-world deployment.
The rest of it appears to consist of "areas that theoretical cryptographers are refining in preparation for real world use". This is the stuff that will be deployed in the real world come 2030.
So, to answer your question: More than half of it is actually used today, and at least 80% of it will be used soon. If you're going to take a course in this, it's better to be ahead of the curve than behind it. (Otherwise, we'll all be suffering through textbook RSA ad nauseum.)