I expect if low end pay at JB stagnates and hiring slows down, you'll see some of the bottom guys bailing for other carriers when offered the chance. I think JB is a great place. I also know several high quality folks who passed on them for AirTran, Fedex, and SWA. One trait of a company without a defined benefit plan is the "perk" of seniority and monetary importance of longevitiy are not as important as at an old "classic" airline with defined benefit (A) plans. People WILL leave for better pay and benefits.
So...if the pay ain't keepin up with the market, folks will bail with their fit. That's supply and demand. To promote stabilty and reduce training costs I expect pay will also go up.
I also expect JB management wants to keep the healthy atmosphere and prevent the company from forming a union. To prevent both, I expect pay will rise. (...I have, however, been wrong before...)
Bottom line is every since the company began, management has "under-promised" and "over delivered" to its crew force. That has built up some trust. Right now, the pilots there (outside looking in...my impression only) have expressed concern but are also saying "okay...you've done us right before, let's see what happens when the jets get here..."
Time will tell. In the meantime--if you think JB is a bad place to be...apply at UPS, FDX, Netjets, SWA, or Airtran. I'll be glad to help you prep wherever you want to go. That aside, the JB guys and gals I've met and helped have all been highly motivated, professional, and proud of their company. I'll bet they can make this work out to everyone's liking...