Speculating speculative speculations
I think in 3-5 years' time, there will be a genuine shortage by anyone's definition. The Big 3 will be alright, but regionals will especially suffer with only their lifers sticking around. A little further down the road, LCC's and smaller carriers will have problems. JetBlue, Allegiant, etc. Then, maybe, a decade from now, the majors might have small staffing problems. I think at worst they'll just decrease frequency to smaller cities. The public will definitely notice though, particularly anywhere covered by Essential Air Service or by a regional jet.