George RR Martin confirms SNOW. Yes, it was Kit Harrington who brought the idea to us. Jun 23, 14:43
Emilia Clarke separately confirmed she knew about it to the BBC, for now says she's "done" as far as reprising Jun 23, 14:45
Also notable that Harrington brought his own guys in so Weiss & Benioff presumably will not be involved in this either {nm} Jun 23, 14:52