I am telling you guys for the five hundreth time, Boeing could SO sell that airplane if they wanted to. Shorten it, and you have a regional jet, a 717-100. For this shorter version, you could get away with using the BR710 engines that are less powerful yet consume less fuel, making the smaller one just as efficient as the larger.
NOW- stretch it and you have a perfect MD-80 replacement. 717-300. Who's the biggest customer? Why, American Airlines, of course. 260 orders at program launch. PERFECT commonality with their existing MD-80s (okay, not perfect, but better than a 737-NG) and more efficient, and fewer mechanicals.
I think these guys are right- the MD-90 program was a flop from the get go. Especially considering that they were such junk off the compass rose. SAS's first two planes wouldn't fly, quite literally, and Douglas had to come out to (wherever SAS keeps planes) and rewire both of them from nose to tail. Also, no one needed one. Delta took... sixteen units. Not very many, folks.
The 717 is different from the 737-600 in the same way that it is different from the upcoming A318. The 717 is efficient for short hops, like between the Hawaiian islands and other routes. Many flights a day- the 717 was designed for 12 flights per day, each one hour in duration. The 737-600 and A318 are designed for longer routes.