Provided nothing is pushed back, the WordPress JSON REST API plugin is being integrated into the WordPress core and is slated for version 4.1.
As WordPress becomes more and more like a PHP application framework, the robustness of WordPress continues to grow. The JSON REST API will be a massive feature that will make creating single page websites and applications a whole lot easier. Being able to fetch a page, archive or single post as JSON and then use that to create fast and lean single page websites will be a welcome addition.
The addition of the JSON REST API plugin to the core of WordPress will also mean using front-end frameworks like AngularJS, BackboneJS, EmberJS and so on, a whole lot easier. You will no longer need to install third party plugins or write your own code, to turn a WordPress installation into an API for an AngularJS service.
The possibility of also using WordPress as a service API and administration panel and using something like Node.JS for the front-end is made a whole lot easier and quite exciting. I think WordPress 4.1 is going to be one of the best versions of WordPress released in a very long time. What do you think?
Now, if we can get the Advanced Custom Fields plugin integrated into the core, I think we will be set for a very long time.