Having a course to do with Scala and Play I feel would be beneficial to many people.
Scala is a fairly unknown language to the wider community but is used by a number of high profile companies such as Linkedin, The Guardian, Netflix plus others: https://alvinalexander.com/scala/whos-using-scala-akka-play-framework/
It’s a functional based programming language that is run on the JVM and has many advantages over Java.
Play is a framework that makes it easier to build web applications in either Java or Scala which is utilised by many companies: https://stackshare.io/play
It is based on a lightweight, stateless, web-friendly architecture. Built on Akka, and provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications.