I would interpret the question as, will the Gutenburg editor be available to edit categories? That is, the traditional category editor supports a textarea field for the description. Can you make it so the Gutenbug editor appears there, too?
Of course the _display_ of the resulting category description (now containing blocks) would be up to the theme, but much of Gutenbug itself makes assumptions that there is code on the front end to display Guutenbug elements.
Probably not many themes display the category description because it is just a textarea, non-wysiwyg. Apply Gutenburg to that, and maybe developers will start using it.
Can one if the developers add this as a feature request? Seems like a great idea, and certainly would be applicable to all taxonomies, like tags, for example. (And look at other textarea fields, like author bio, media caption/description, menu description… if we have to have this new editor in the first place, might as well be consistent.)