I’m aware of the Classic Editor. Gutenberg is unlikely to fit my work any better in three years when it is no longer supported than it does now, and the Classic Editor is unlikely to do anything about the further phases of Gutenberg being pushed on everyone.
ClassicPress is staying compatible with WP 4.9.x for as long as possible, but I guess, sadly, I can’t count on Nirvana in the long run. Thanks for the answer, I’ll start the search for a theme that is going to specifically support ClassicPress.