I think Notch is supposed to be focusing on bug fixes right now, I doubt he'll implement that boat thing.
If you read even a little of it, which is all I did, you'd read the whole part where he acknowledges this would probably end up it's own update if at all. It is never said "This must be done before full release!" It is just an idea for how big boats should be handled. That's like saying "We made this new toothbrush that can eliminate brushing forever!" and going "Well, we can't get the product in by next quarter, so we're probably not going to make it at all." Of which, the response would be "Well obviously, I'm just saying this is amazing and we should work on it."