Thing is, “A Star Wars Story” was only used for marketing for Rogue One. The movie itself is just Rogue One on the title card, not even Star Wars: Rogue One. Like how Die Hard 2 is just Die Hard 2 - the “Die Harder” part was just a tagline for marketing purposes that was always put right under the title so everyone calls it that. Or the first X-Files movie - “Fight the Future” doesn’t appear in the movie itself, just The X-Files.

If Solo follows suit with Rogue One, the title will just be Solo. “A Star Wars Story” is just a marketing tagline.