I think the article starts from two wrong premises, first that Julia will become the language and second that it will do so in only a few years.
As to the latter: As others in this thread have said, language adoption is a non-linear process and starts very slowly. In fact, given Julia’s age I think adoption is actually growing a lot faster than for “yet another xyz” languages and more in line with “breakthrough” (at the time) languages such as Java, Rust or C++.
Concerning the former: I think it would be overly optimistic and also completely unnecessary to assume that Julia will become a majority language in the vein of C, C++ or Python. The language started out with a very clearly defined niche in mind and success should be measured relative to that niche.
And within that niche, I think Julia is a game changer and my prediction is it will become the language within the next ten years or so.
In any case, all of that is kind of academic from a practical and the OP’s question’s point of view. What matters, though, I think is that Julia is in no imaginable way a dead or dying language, to the contrary. That means the only relevant consideration for the question whether to learn/use it is whether it works well for your project.
Finally, I want to add some personal experience. I have been writing simulations for 30 years, mostly in C++. I actually always liked C++ even though it can be incredibly annoying at times. But as soon as Julia was fast enough (within 10-20% of C++ for my problem area) I switched and didn’t look back. And I have to say it was a close to life-changing experience.