Any forcast for hiring is as reliable as a long range weather forcast. There are way too many variables to make a solid guess.
1. Oil prices
2. Global economics
3. Terrorism
4. Global pandemics
5. Inflation
6. Availability of credit
7. Possible chapter 11/7 of several airlines in the very near future
8. New entries into the market/Cabitage

Any one of these factors will greatly affect airline hiring in the next few years. I'm sure I forgot several other factors too.