While the enabler of the regional airline model is the seniority system I also understand it's not likely to go away, especially at the majors where we like it the most and it serves long term employment.
What I think should happen is to see the unions support a relaxation of the seniority system at the regional level to see what happens...after all, it can't possibly get any worse.
I think it would be good for regionals too...in the short term...as they could hire experienced captains directly into the left seat to greatly reduce training costs. This would solve the alleged "pilot shortage."
In the long term I think you'd see higher salaries at the captain level and the business model fade away slowly as majors began to re-absorb the flying back from the regionals.
If majors hired pilots based on qualifications and merit without preference to PIC jet time (like they did in the old days) then first officers could still consider the regionals a place to build time to move on to a major.
Get rid of the crazy and irrational entitlements based on seniority at the regional level and allow the regionals to upgrade pilots based on experience and qualifications rather than a number...this would be beneficial to everyone.