I don´t think that the Boeing 717-200 will laat much longer. It doesn´t fit into Boeing´s philosphy and even worse: it does steal orders from the B737NG especially the -600. And to market the B712 huge marketing efforts are necessary which are very costly, especially now when airlines are thinking twice about new orders. And to break-even the project needs a couple of orders (to be exact more than 150), extremly unlikely to be ever reached. For Boeing it is likely more satisfying to dropp of the low-yield regional airliner business, leaving thi market to the specialized players, and to refocus efforts on the B737-600, the more promissing product.
To me it seems that the end of the B717-200 is very, very near...