Realistically, the selling point of Drupal is the strong integration between the front end and the back end - if Headless Drupal becomes the norm, there won't b

Realistically, the selling point of Drupal is the strong integration between the front end and the back end - if Headless Drupal becomes the norm, there won't be a lot of good reasons to deploy Drupal on the back-end instead of say, Rails API. If the Drupal project gets solidly behind Angular, React, Ember, or something else, and Drupal 9 modules support client-side as well as server-side rendering, this could be a very interesting development.