It depends how much you like working with legacy code, and how much you love C++.

If you stay the "C++ expert" route you will always have a job, but it will be every more gnarly legacy code. Because those who had relatively good legacy code are also those who are going to find it easiest to migrate off of it.

Judging by what happened in Perl (the example that I know best), I'm guessing that most developers will leave C++. Mostly for languages in a similar space. A lot will go to Rust.

Depends on your opinion of Rust and the associated community.

C++ jobs are not going anywhere, quite the contrary. A lot of systems won't be rewritten. Besides, at least at the moment "C++ expert" is a perfect background for becoming a Rust expert should the want arise.

Rust *is* much more enjoyable to program in than C++, though