I think the industry is in a big change, I think the definition of mainline and regional is going to change and become more blured.
For the next two or three years I think you might see a pretty even mix between regional and mainline carriers using the 175's and 190's
As for the pay, I cannot really say, I think that pay is going to be pretty level in comparsion to what it is now.
If I had to guess, managment is basing pay somewhat on complexity of the jets, so maybe more automation equals easier to fly which equals less pay.
I am almost certian someone is going to blow holes through my thoughts.