I don't have to 'know future plots' to understand that Robin has no relevance to OUaTiW's story going forward. All I have to have knowledge of is what the show's premise is and what it's already done.
Unless Alice and Will somehow end up in the post-Curse Enchanted Forest (which isn't likely), Robin Hood won't be showing up again on this show. It's as simple as that.
Anyway, I've said what I wanted to say.
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"Oh, brilliant" - Thirteenth Doctor
"Half an hour ago I was a white-haired scotsman." - Thirteenth Doctor
"I know exactly who I am. I’m The Doctor." - Thirteenth Doctor
"Two hearts. One happy. One sad." - Thirteenth Doctor