Of cause there aren't public drawings from the manufacturers yet. The Boeing project is called "LightTwin". Another one is "New Small Aircraft".
Boeing is trying to make up its mind on what to do, because they see a market for aircraft taking more further then the 737/A320. Airbus' A321 is taking it.
On the other hand the 737 appears to approach its expiration date more rapidly then hoped. Saying it ain't so probably won't lead to a satisfactory market share.
So we probably see some action here in the next few years
