Captain Liam Shaw went from being a disliked captain who opposed Admiral Picard and Captain Riker at every move and refused to acknowledge Seven of Nine {Jeri Ryan} by her preferred name. He was sarcastic and cold and didn't endear himself to any fans...at first. Over the course of the brief season of Star Trek: Picard, Shaw was redeemed and even handed over the reins of the Titan to Seven of Nine and recommended her to be promoted to captain. His redemption arc was well-played in so few episodes. Unfortunately, Captain Shaw was killed before the season ended, and while Terry Matalas and Stashwick have discussed ways to bring the captain back, it looks like it won't happen unless Star Trek: Legacy gets greenlit.
But there are other ways the franchise could reintroduce this incredible character even without Legacy. Holograms never go out of style on Star Trek, and neither do alternate timelines. There is time travel, of course, with the potential for even the crew members of the Enterprise under the leadership of Captain Pike [Anson Mount} to meet the captain, perhaps before he encountered Picard as Locutus of Borg. If that series can bring animated characters to live-action, nothing is off-limits.
Perhaps Star Trek didn't expect Shaw to become such a well-liked character, but now that he is, the powers-that-be should figure out a way to bring him back to the universe even if only for a few episodes. That way, he could stay fresh in the minds of viewers. I mean, anything is possible. Starfleet Academy is bringing Robert Picardo's character, the Emergency Medical Hologram, to the 32nd century. Who's to say that Shaw couldn't be a lesson in history for the cadets, or an episode like Star Trke: Voyager's "Flashback" could play out in a current or future episode or movie.
Now that fans have expressed their like for this character, it would be a shame to waste him, especially considering how much we have yet to learn about him. So, no, Legacy isn't the only way Shaw can be brought back. And I, for one, hope to see him in the future.