Every web application that powers the web, CSS, HTML, and JS is about to get turn on its head with the introduction of HTTP/2. The basic of HTTP/2 are simple and yet amazing. It is much more efficient in comparison to HTTP/1.1, which only allowed for each connection to a server to handle one request. HTTP/2 can serve multiple requests all at the same time. Connections can  also push a representation from servers to clients.
This changes everything about how applications are used to build the web. With HTTP/2 there is little advantages from, putting <script> tags in HTML, inlining of resources, or compressing JS files. Rebecca Murphey shares the new, best practices to keep in mind when deploying applications with the new concept of HTTP/2
For the record, there are still huge gains to be made with JS compression; it is JS concatenation that would become redundant. Server smaller chunks of JS allows you to leverage caching, but minification will still reduce the total file size of sites.