If the environment was different, one could see a LCC like JetBlue having potential interest. But I think near term prospects would be slim for this.

Other option could be enticing an airline to move from C or D if those terminals are space-constrained. I actually like the new A and B terminals at BWI.

BWI has never been able to get much traction on international flights. With E being on opposite end of the airport and needing to exit the secured area, it would make things more challenging for connections. I also think that a European LCC which would require another connection once crossing the pond may limit customer interest somewhat, especially with WN cutting back on longer flights.