So one potential problem is not clear what should be taught next. Many programming languages are quite complicated because of the incorporation of various libraries/packages.

A couple of questions you might like to think about:

1. What would exactly like taught?

2. What is your purpose for learning programming? i.e. Do you have any particular area you are interested e.g. data science, embedded systems, networking.

You might be interested in taking look at various free online resources as a starting point.

e,g. Coursera, FreeCodeCamp

What I have listed should serve as a starting point. If you go with Coursera, I recommend giving Discrete Optimisation a go. Note that lot of courses on Coursera are paid, however with a bit of searching you should find free courses.

I Agree With the Original Poster I believe Khan academy should create courses for different languages like C++ Java Etc and Maybe for different Niches like software enginnering Data Science AI etc