US has indeed looked at the Q400, but I wouldn't expect an order at this point. Dave Siegel was very interested in the aircraft, but Bruce Lakefield does not seem at all interested in a new turboprop order. (I do understand, however, that Piedmont is looking for some additional secondhand Dash 8-300s.) Perhaps when US emerges from bankruptcy and gets a new CEO, they'll reconsider the Q400. I do think it would work well on some CLT
markets like OAJ, HHH, EWN.
As for the EMB-190, US will no doubt be shortly ordering them, either for its MidAtlantic division or to be flown by Republic. US is permitted to operate up to 60 total EMB-190s as US Airways Express, with up to 25 of them being operated by an affiliate carrier like Republic.
US does not currently have scope relief for the EMB-195.
I'm the expert on here on two things, neither of which I care about much anymore.