It's easy to harp on PHP but I wonder if we're going to get this kind of vulnerabilities in languages like Python or Go soon too.
The way things are going, I imagine there are going to be vulnerabilities found in everything
Probably not. PHP is so badly built these kinds of things happen frequently.
PHP is worse in this aspect with its long tail of legacy and staying close to C. It's absolutely possible that memory-unsafe Python interpreters could have something vaguely similar, but it's much less likely. Plus there are Python interpreters in memory-safe languages.
In any case, memory-unsafe codebases will continue to be a significant danger. Be it in interpreters or anywhere else. Just like they have been for the past 20+ years.