I have heard conflicting reports as to the scope exemption that AWAC had. Most people think it is still in effect, though I had heard that it was only good for those 18 airframes. Others have said they could be replaced 1-for-1. Not that I advocate it either. I would rather see mainline jobs for all of us in the future, not large RJs.
With that said, AWAC and United have always had a different kind of relationship and even though AWAC is not currently flying as United Express there is still a solid business relationship between UAL and AWAC regarding ground handling. And when the contract ended a couple years ago for flying the company was very clear that they intended to keep a good business relationship with United should the opportunity arise to fly for them again.
Personally, I would love to fly as United Express again. I liked it much more than what we currently do on the East Coast.
Not that I want RJs to replace 737s......