In reply to bobbi.

Matt initially stated at WCEU next year he'd like to see at least 100l many sites running it prior to releasing it in core but I think this was just because it was in a QA answer. I totally understand things shift over time. However, at the time of this comment it looks like only 8k+ https://wordpress.org/plugins/gutenberg/

I don't think 100k is necessarily a number that has to be held to steadfast but at least more than 8k would be nice. :)