Boeing would be better off listening to ther customers.
Making a 717-300 is likely to help sales of the 717-200,hell,it might become a big seller.
Airlines like a common type,have pilots be able to fly different types,sizes etc,look to the 757/767 and bar the A300/310 the same pilot can fly the entire Airbus range with minimal training.
Not just that,spares,common to the -200 and -300 for example.Same engine types etc,the list goes on.
Its highly unlikely,almost non existant as a possibility,but,Airtran could go to Airbus,get a sweet deal and dump Boeing.
The econony is on a downer,but making a 717-300 now could place Boeing in a better position once everything picks up and the airlines get their cheque books out again.