In reply to Donna.

Ever thought about the developers who are creating huge sites right now for clients, or who just finished some? Now these developers are wondering how to explain that everything the client just paid big money for, and all the training that went into learning how to use their site, is possibly going to melt into a big pile of goo, whenever Gutenberg comes along. Or maybe not. But maybe it will. And maybe it will cost a lot of money to fix. Or maybe not. More confusion.

^ This. Backwards compatibility is a huge concern of mine with Gutenberg at this point, especially for sites that make extensive use of page builders or plugins like Advanced Custom Fields.