I personally like the new direction of WordPress with Gutenberg. It's the need for sure to make it future proof and align with the modern website builders.

Of course, all these decisions are hard to implement and not every legacy can be retained.

But, definitely, things need to be progressed well communicated so that the 3rd party developers can take proper action to make their these & plugins work with the new single app WordPress & also plan ahead on what to work on and whatnot.

As in this case, I can see some theme developers are still working hard on building or upgrading the header/footer builder in the customizer and also improving that to use Gutenberg components in the customizer. If it will be deprecated, they need a clear announcement (I guess) so they know what things to work on making their theme future proof.

That said, I personally think WordPress is heading in the right direction and it is opening up a lot more new opportunities for developers like me.