You probably know well HTML’s way of embedding/transcluding images and other material, and
iframes even allowing to interact with other pages that aren’t part of the current one, as lower, simpler forms of transclusion. While Ted has several descriptions (or focus on different aspects) of the concept, if I understand correctly, the higher forms of transclusions, also similar to Alan Kay’s object manipulation and Bret Victor’s demonstrations, is probably roughly along these lines. Maybe having one global (maybe federated too, I’m wondering?) live resource and change/adjust it from many places, as an integrated part therein. Not so much everybody jumping on the same shared Google Doc, but composing “pages”/UI from transcluded parts/components. But I don’t really know for sure and authoritatively, more an indication of general direction.