The Phactor is going to start growing his tree house right now because clearly this tree house is going to take awhile. This is a pretty nifty idea, but why use cherry trees? The designers think it will take 100 years to get cherry trees to do this, but you can probably do this with willows in no more than 20 years except you won't get those pretty flowers. Some time back the Phactor showed a less aesthetic example, but one grown in far less time. And the best bet might be a fig, but of course you'd need a tropical climate to grow a fig treehouse. Actually saw a similar structure once, but memory fails me where, a patio room whose "roof" was constructed of wisteria ribs that originally were trained to a frame but now had become self supporting.