I think Jon Snow's return in 'A Dream of Spring' is practically guaranteed. George R.R. Martin doesn’t kill off major characters without purpose, and Jon’s death in 'A Dance with Dragons' was too abrupt, too unresolved. Melisandre’s presence at the Wall hints at resurrection magic, and the foreshadowing in earlier books about 'waking dragons from stone' could tie into Jon’s rebirth. His parentage reveal is also critical to the endgame—ignoring it would make no sense. The show’s adaptation, flawed as it was, confirmed his role in the Great War. The books will do it better, with more depth and fewer shortcuts. If you love political intrigue and mythic cycles, read 'The Accursed Kings' while waiting—it’s like GRRM’s historical inspiration.