> They cannot lose interest or make self-destructive decisions because the IDEs are their core revenue stream.
But this can be said about Microsoft as well. IDEs are not the core of their revenue stream, but they're near the core, because "developers, developers, developers, developers" is still true. They're a software company, they make operating systems, a cloud platform, and hardware. They need to provide developer tooling. If IDEs aren't their core revenue, they're certainly near the core. If Microsoft hasn't been making money on IDEs lately, they have in the past, they see other people are, and they're certainly going to try and get back to that if they can.
They could try to do a reverse JetBrains and introduce an enhanced for-pay version. Supposedly they're already starting to do that with Python support, it seems. But starting commercial and going free is a lot easier than starting free and going commercial, in terms of user loyalty.
Meanwhile JB survive the assault, continue to invest in their core product (which have been incrementally evolved for decades and were never rewritten from scratch), and come out the stronger party. They cannot lose interest or make self-destructive decisions because the IDEs are their core revenue stream.