Jon Snow is the actual Prince That Was Promised. Rhaenyra having Aegon's dream passed down to her doesn't make her the prince that was promised, it just makes her a link in a chain that leads somewhere else entirely the actual prophecy was never about the Iron Throne. it's about uniting the realm against the threat from the far North, and Rhaenyra never fights that war. she fights a civil war over a chair, and it ends up wiping out her family's dragons instead of saving anyone. the bloodline mechanics point somewhere completely different too. a woods witch foretells the prince coming from the line of Aerys and Rhaella, and Jon is exactly that, born from Rhaegar and Lyanna, the literal Song of Ice and Fire made into one person Jon's also the one who actually does the work the prophecy demands. years spent warning people who won't listen, building the alliance with the Wildlings, bringing Dany and her dragons north to fight the Army of the Dead. Rhaenyra inherited a dream. Jon lived the prophecy and fulfilled the prophecy