If you dig through the math a little, this is not quite that simple. And the brunt of the differences are also not an even burden between CA/FO rates. FOs at regionals are far worse off than FOs at majors using any math. The pay in dollars drops off a cliff, but the pay per aircraft size (pay rate divided by seat) is more messed up than drawing a straight line to make things better. Equivalent longevity XJT captains make more per seat than UAL captains, believe it or not. And don't forget that someone who makes 100K at a major is far better compensated than the same 100K if paid at a regional. The retirement alone increases major compensation 13-17% in B funds and superior 401k matching schemes. Better respect through flight benefits etc...

And newhire pay at UAL is $60/hr. Average narrowbody has say 140 seats there. That's $0.42/seat first year.

50 seat RJ at $0.42 per seat newhire pay is about $21.40. XJT pays $22.

So your linear math is already in place today on current pay scales.

My point is, the solution isn't drawing a straight line if the line goes below an acceptable salary. Regionals must pay MORE per seat to crews if they want to operate RJs. Add fuel consumption per seat plus increased crew costs per seat, and you see why RJs are going away.