> A fear of breaking things means WP shies away from large-scale changes that would help it become a modern-looking PHP app.
They are strongly advocating Javascript as the future of WordPress right now, so I'm not sure if they would like it to become a modern looking PHP application.
I'm working on some of these "future of WordPress" projects right now, and I don't think PHP is going away any time soon. The JS-future for WordPress is more to do with the editing experience than anything else -- the entire rendering pipeline, backend, and rest API is still PHP, and I'm not aware of any plans to change that.
The main difference with the future of WordPress is that instead of templates (which describe the structure of a site) being written in PHP, they will be written as blocks so that they are user-editable. I would say it's more apt to say that "blocks" are the future of WordPress. The block editing experience is written in JS, but serialized block markup is backwards compatible with HTML, so no JS is needed to render blocks once they are serialized.
They are strongly advocating Javascript as the future of WordPress right now, so I'm not sure if they would like it to become a modern looking PHP application.