Well, I would not be surprised to see Air Wis get into larger aircraft, esp since the 50 seat CRJ is falling out of favor. It would be smart on their part to expand into other areas.
IMO, with the size of the E-190 order, it is less likely that their will be a sizable order of CRJ-900's, even though the scope may allow for it. Afterall, as it was pointed out before in this thread, the B737's appear to be staying around for now and the CRJ-900 is rather limited in capability.
I would bet instead that AW gets into either the E-170/175 themselves (cannot get the E-190), and I also think their is a good possibility that they may purchase themselves a larger precentage of US Airawys' Express flying with a purchase of PDT and/or PSA.
While either sounds like a dumb move alone, if purchasing one of the wholly owneds with the ability to add 70 seat aircraft at either carrier (CRJ + DHC-8/400), then it becomes a much more attractive move.
IMO, Airways has made thier intentions clear with the purchase of the E-190, and any growth for the express carriers will be in the 70 seat range, either with props or jets...