ATL2CDG, you make a very good point.
However, some of my point is that regionals are flying more routes not because of aircraft economics, but rather, because the cost of operation, with the very low regional salaries, totals out to less.
In the 'traditional' sense, instead of LAX-BOI, you'd fly LAX-PDX or LAX-SEA and then hop a regional to BOI. This worked in the system where it was expected that everyone would migrate to majors.
But you essentially have to force the corporate owners to maintain the mainline. Why not? Because otherwise, without those unions, salaries will fall. Corporate would love to pay everyone based on the regional payrates (and maybe bump the top 20-30% for flying a 767, for example).
What's happening right now is, where possible, the opportunity is being seized to force the payscale downwards, by furloughing mainline pilots and increasing regional size. All the talk of 'bringing the bottom up' is nice, but that's not the intent of corporate headquarters. That's NEVER their intent. The way to get pilots better paid is to REDUCE the size of the regionals -- let mainline pilots fly anything 50 pax or more, and any jets, for example. Getting pilots into mainline jobs is by far the best way to improve their quality of life, rather than trying the 'well, let's get everything flown by regionals, and then maybe they'll increase the payrate.' That, in fact, is simply reinventing the existing situation.
In my opinion, the regional concept is being abused for the financial advantage of the corporate headquarters. Sure, that's their job, but it's the job of the pilots union to protect wages as well.
And lastly, the salary figures are misleading when you factor in that the top end folks don't usually get there until 4 or 5 years before they hit age 60.
Heck, I know plenty of 30+ RJ captains right now who haven't even been able to make the transition. Given the current economics, they won't be mainline CA's until they are 40-44 years old, then they've got a whole 16 years until they are booted. (in the US, that is)