The advantage to this is flexibility. Every content management system has it’s limitations, many of which can be overcome by a front-end infrastructure that only exists as a detached presentation layer for content that is served from elsewhere.
The word on the street is that React is the leading contender, due largely to the fact that Automattic uses it in their projects. I’m concerned that this will be the case, and that the WordPress project is about to make a very poor decision.
Issues with React
React also has a steep learning curve. This is also a confusing point for me, as another central tenant of the WordPress philosophy has been to make the process of learning easier for developers new to the platform. React introduces an extremely opinionated methodology, to say nothing of an opinionated set of tooling, that seems to fly in the face of what WordPress has done previously.
In addition, I’ll admit that I have philosophical issues with React. Introducing another programmatic layer to the front-end stack to render the DOM not only negatively impacts performance, but also is, in my opinion, a very poor separation of concern. Let the DOM be the DOM.
The final decision about the core framework is set to be made at WordCamp Europe, so we should have an answer soon. For the sake of the project, I truly hope that the answer is Vue.js and not React.