Why would an airline deliberately undercut themselves by giving one regional a huge advantage over the others? It seems to me like the moves they're making are meant to stabilize and preserve the current regional model, not destroy it. United is rumored to be working on flow through agreements with all of their regionals not just a select few.
I think in the future it won't matter which regional you go to because they'll all have the same paths to mainline. You pick the one that works for you or is closest to where you live and your time spent there will be like one long probationary period. Interviews and selection won't matter so much because by the time anyone actually "flows" they will have been thoroughly vetted for years. This is just my guess on where the industry is going.
A flow-thru is significantly different from what they want to do. If successful, it will be industry shattering and set a whole new standard. Every other "regional" will suffer massive virtual overnight attrition as qualified proven pilots beat a bee-line for Eagle/AA.
The ensuing attrition will force industry consolidation on proportions not ever seen before.
That said, there are obstacles, and nothing is guaranteed. However, they do have a clear plan, and have been taking the steps necessary to implement their agenda and attain their objectives.