I hated Lyanna but still didn't want to see that. lol
I don't think it was a good episode though... So. many. Deus Ex machinaas.
But the idea is right though. Our heroes at Winterfell survived the army of the dead only to be slaughtered by Euron and Cersei. Yara Greyjoy might have a big role when that happens. God please not another Deus ex machina.