Wasn't it just that the prophecy from that crazy bitch who killed her baby with Drogo put some conditions on it? Sure, it sounded impossible, but if taken metaphorically it might happen. The sun rising in the West is maybe Jon Snow returning as the Chosen One or whatever the Hell he's supposed to be, the seas drying up could be the "Dothraki Sea" becoming a desert, the mountains on the wind could be some reference to Gregor Clegane's monstrous body being dropped from a dragon flying high in the air...you know how this shit works in fantasy.
ἡ δὲ κἀκ τριῶν τρυπημάτων ἐργαζομένη ἐνεκάλει τῇ φύσει, δυσφορουμένη, ὅτι δὴ μὴ καὶ τοὺς τιτθοὺς αὐτῇ εὐρύτερον ἢ νῦν εἰσι τρυπώη, ὅπως καὶ ἄλλην ἐνταῦθα μίξιν ἐπιτεχνᾶσθαι δυνατὴ εἴη. – Procopius
Ummaka qinnassa nīk!
*MySmiley*