> in the same way that Gutenberg has challenged page builders.

I'm not sure I'd say it's "challenged" them, unless you mean in the sense that the morning traffic is a bit of a challenge.

I think it might be more accurate to say that Gutenberg has shown the page builders to be valuable and far in advance of what Gutenberg can currently do. Of course I hope and expect that to change, but at the moment based on what we work with I would predict Gutenberg to match Elementor in around 3 or 4 years time.

I've implemented Gutenberg solutions for smallish low traffic sites and in every case I'm now being asked to find an alternative. Inmany cases that's because updates have left Gutenberg pages in a broken and uneditable state ( that means an update to WP, to 3rd party blocks, or otherwise).
The clients who are simply pasting text from Word, they want Classic Editor. The clients who want to get involved with semi-locked down page layouts and WYSIWYG are much better served with Elementor, Divi or some other integrated and well supported solution. It's robust, it's WYSIWYG, it's actually got documentation! (note: there is zero end user docs for Gutenberg).
The clients who have used Gutenberg are now soured on it, and will require a lot of convincing to try it again in future. Too many broken pages, too much ringing me for support.

So, I would not say that Gutenberg is a challenge to page builders.