A lot of people may chime in with detailed answers to your questions, but the cold, hard truth is no one on this forum or even management types know what is going to happen next week much less in 5-8 years. There will be dire predictions and those with rose-colored glasses until they die. You will pass on young and stressed out if you try to figure out this industry. I've never gone wrong putting my family first in all of my career decisions so that's my only real advice. They will be the only people you have left if your career moves end up being horrible in hindsight.

Bottomline is that the way things are at this very moment, absent any major financial meltdown, domestic terror event, or a change in retirement age, you will have your choice of majors/legacies to go to. In the mean time, as far as regionals go, pick one that you think you'd be happy with if the music stops. A lot of people felt they got hosed by age 65 and the 2008 recession and were forced to spend many years more at their regionals than they expected. If any of those 3 events I listed above occur in the next few years, we could see the same thing happen.

The cliched, yet very relevant, saying is that you will not know if you made the right choices and had a great career until the day you retire.