"But even if Swift remains an Apple-only thing, it’s impact could be greater than any other language that has sprung up in recent years, and it may achieve mass adoption faster than any language in modern history. "

I don't even like Node, but it is hard to imagine that Swift will get adoption faster than Node.

If 100% of Objective C users switch the adoption could be fast since you'd have a new mature-ish language as the preferred language for a large install base. But I don't see the libraries and modules being there to allow most devs to just switch right away.