I understand the desire not to wrap every single thing up, but by having him live, it's already an invitation to reintroduce him into the story. To have him bring the plans to the Rebellion not only preserves his dignity, but in fact raises his villainy lavel at least 30 points. Even if he survives, good storytelling almost requires that we know what happens to him. Even the bad guys who survive in the movies usually escape to who knows where at the end, but Fett would simply disappear in the middle of the movie. If nothing else, he should seen during the Battle of Endor, then he chickens out and jumps to lightspeed. Too much head-scratching at the end of a story is no good either.