In reply to John Teague.

I'm sorry, perhaps I misunderstand you, but when you say "a laundry list of core issues", it sounds as though you are describing those as out of scope of the editor rebuild. If so, I would argue that a move to structured data requires revisiting the incompatible parts of core, rather than treating them as immutable. Gutenberg is a fundamental change to how WordPress works, and a major version is the right time to make sure it is able to integrate tightly and set a smooth path forward.