Every AC 84 and 85 on the 763s I've been on in the last 3 years, 8K had a blanket curtain hanging to section off the seat. I always saw it when boarding. On at least one occasion, both 7 and 8 K were closed off. (I'm partial to 4, 5 or 6 A)
Since some of the new equipment have bunks, it will not be an issue. Me thinks.