I think the way forward would be for WordPress hosting to come with a version of node.js with standard packages which plugins can use, in combination with the n

I think the way forward would be for WordPress hosting to come with a version of node.js with standard packages which plugins can use, in combination with the new REST API. So even if we would move past PHP we wouldn't move past WordPress, its database, and the basic ways it stores and describes information. No need to reinvent that wheel if it works well for your site or product.