As far as I understand it, if you install the Classic Editor now and activate it, you can then run WP5 with the Classic Editor and switch to Gutenberg any time you like in the future. As stated by John Huebner earlier in this thread – support for the Classic Editor has been declared as ending in December 2021, as WP see this as an interim measure and do not intend it as a permanent option.
My current plan is to run WP5 with the Classic Editor in the short term while any potential issues are resolved. I have been using Gutenberg with ACF Pro and it really is great with loads of potential. I fully plan to get my clients using it as soon as possible.
I’ll be testing it in staging environments of their websites before switching to it on their live sites though.
