My firsthand knowledge of such things is quite stale nowadays, but I get the impression the RH desktop group is barely on life support at this point. That GTK4 happened at all strikes me as surprising, but could be interesting long-term in terms of modernized GPU support for the toolkit attracting new usage/developers.
The real question is do enough people even care about GTK anymore to make use of it in the future. I'm inclined to believe the current crop of devs want $hipster-language-native GUI packages. Not awkward quasi-"idiomatic" bindings and FFI wrapping an archaic C library like GTK/glib.