If you have not already, I encourage you to read through the Editor Technical Overview and check out the great work so far in the initial Gutenberg prototype. Progress on the new editor can also be followed on the GitHub project. While the technical overview focuses on what obstacles are faced before forming opinions on the correct way to solve them, it does not focus on the actual technology requirements of the deliverables. As contributors start to create a new and improved editor experience, these technical requirements should be clearly defined and agreed upon so that decisions and progress can be made.
Accessibility, for example, is one technical requirement. All new features must pass WCAG 2.0 AA.
Browser support is another technical requirement. A few lengthy discussions have occurred within #core on Slack and within an issue on Gutenberg’s GitHub. The discussions weigh the pros and cons of dropping support for older browsers in order to use features only supported in newer browsers to improve the editor. It is a tough decision to make because the editing experience will become less useful for a small percentage of users.
This post will attempt to summarize the discussions