The gimmick was ripped off from A Prayer for Owen Meany, but John Updike was hot Eastern Bias garbage so good for them. In fact I'm sure Updike ripped it off from someone talented.
In time travel terms: Future Hodor's trance state connects him to Past Hodor for just long enough that at the crisis, when all that matters for him to hold the door, that encirclement of his Being is participated in by Past Hodor, turning him into an instrument to accomplish that single purpose for the rest of his life.
Which, given what a pathetic loser Bran is, is a waste of a perfectly good life, even if it's a prophetic commentary on the terrible waste of human potential in a unequal economic and political order. Come and see the violence inherent in the system!
I loved the play. That is exactly how it would go down, too, complete with fart jokes. I am impatient for The Girl to figure out she's not cut out for this faceless silliness. Tell them "not today." You be you, girl.