Demand wouldn't decrease because of more developers being on the market. Supply would increase. Just because any one developer might be individually in less demand doesn't mean that demand for developers has decreased. Yes, this would still depress salaries for developers.
Having said that, there is no fixed amount demand for developers. If development resources are a bottleneck for development projects moving forward, there being more developers may actually increase demand. This comes about as projects that otherwise wouldn't be started do get started and may, themselves, not be able to be fully staffed even with the new blood. I don't know that this would actually happen... but then again I suspect the Japanese don't really know what will happen either.
You can't just look at the two values of current demand and current supply and extrapolate that into a vision of the future... there are many, many more variables than that.
Yet, I think that robots don't create as many jobs as they take.
In any case IoT is doing it's best to massively increase demand for programmers. Once everything is sufficiently IoTified programming will be as common a tool as a hammer.
(We have pretty widespread teaching of programming in high schools in Germany. Doesn't help too much.)
That also includes keeping the loudly howling minorities for any given topic in check that raises hell whenever a person in public view seems to disagree with them, thereby teaching such people that lying and pretending is the best option.
First-past-the-post basically forces you to vote for the idiot, or risk throwing away your vote.
Any effects of education are swamped by the differences in voting systems. Germany has Mixed-member proportional representation (https://en.wikipedia.org/wiki/Mixed-member_proportional_repr...), which leads to a multi-party system.
The US has some variation of first-past-the-post. Especially together with the primary system, this rewards people for pandering to the base.
No argument that STEM education was good in the East - I even have proof. Immediately after reunification German magazine "Wirtschaftswoche" (Businessweek equivalent) sponsored a very big test of students who had just finished high school "Abitur" in Germany) in East and in West Germany. It was tens of thousands of students. The result was that East German students wre significantly better in everything STEM, and worse in "language" (not just English, also in the use of their own language - so they were good engineers and bad at marketing and PR, to translate it to job profiles).
However, that is not nearly enough for success, the main reason Western firms outsource to the East is price. Competence is necessary but not sufficient. Most of the software boom in the East is fueled by demand from the West.
It exposes you to entirely know ways to solve problems, a basic understanding of computer science on a societal level would be amazing.
Not everyone will know how to be a plumber, a doctor, an accountant, or a software developer, and that's just fine. Most people should know how to read and count and that is also fine.
That said, programmatic thinking itself is much simpler. Learning how to think algorithmically and think about things like recursion, iteration, functional abstraction, etc., are definitely things everyone can learn to do. And this sort of thinking is valuable in areas other than software engineering. The weakest thing you can claim is that knowing programming lets people write programs, which is somewhat popular hobby activity among people can do it regardless of their profession, and something that there's some value in given the success of IFTT, Tasker, and similar systems that either approach or are actually programming.
This has nothing to do with skill. As long as demand is higher than supply for your job you will be well paid. Median wages for lawyers are lower because there is an oversupply of workers on the job market.
Like more javascript frameworks?