Dunno. I don't see as much risk there as you apparently do.
It's my opinion that DEN is over-served. It's one out of several regulation era hubs that existed because of geography and poor aircraft performance. Just like STL, MCI, SLC, DAY, CMH, IND.
As a metro area, with 2.6M people, it's smaller than MSP, STL or BOS.
Certainly big enough for a fair degree of nonstop service, but has never really been able to justify 300+ flights a day with two hub carriers, much less three.
If a deal happened, there's very little connecting traffic that couldn't just as easily move via PHX or DFW. Keep the codeshare with Great Lakes, and pretty much all the same bases are covered.