Stating that this is the "future of web UI" implies that most of us will have to develop duplicate logic on client and server side, possibly with different languages (as the author actually does). While he mostly talks about the validation, it seems to me that just plain validation will not suffice - we would have to keep lots of business logic duplicated as well. And "duplicate" usually meaning "almost the same, but with bunch of edge cases not behaving exactly the same way".
Am I the only one who does not like such outlook?