We actually have a second generation of the aircraft... but its not a complete update like the E2. The version SkyWest has (sans 103SY) has a 6.4% average fuel efficiency improvement over the original model. It includes a new winglet and aerodynamic clamps, as well as other upgrades such as LED lighting.

The E2 is more of a clean sheet aircraft that will be re-engined and have a new wing.