Wouldn't the most strategic programming language to learn be the one that is the next Java?
Learning one language is unacceptable. There are many different tools to use that are way better than Java in different circumstances. Not to mention you can learn things that Java doesn't even start to handle.
IMO... if you're going to learn one language. Learn JavaScript. It's not the nicest or coolest but it is on almost every device in the world. You're diagram is now null and void.
On the integration front, one thing I will also add is that in .NET integrating Lua with your program feels pretty close to being a first-class citizen. Very nice.