The new runway project is fully underway. West of the airport it's a complete mess. Backhoes and bulldozers are in great abundance moving earth all over the place to put the tunnel for Lindbergh that will be under the new runway. I don't know if they can reasonably stop or not.
I fly MDW
about five times per year, and sometimes if I check in early I walk from the East Terminal through the gates that the charter companies use, and into the end of the Main Terminal (D gates, I think it is). There are lots of American flights going all over the country, and indeed, much of it is connecting traffic.
Personally, I foresee another discounter or two coming in (AirTran and jetBlue come to mind, and Frontier is another possibility) and WN
expanding slowly and using the three gates in the East Terminal that are currently unused.
Time will tell, of course, but I think folks in St Louis are still going to have viable travel options. It just won't be a connecting hub anymore.