Jetblue has announced on board wines and shopping options as ways to slowly get $5-$10 from passengers. Not all of this incremental yield has to be from ticket prices. Look at the extreme of Ryan Air.

Flying to underserved cities and competing with NW seems to be another way to push up overall yields. If the EMB technical problems are ironed out, that'll help increase service to cities where competition is minimal and yields are much higher than current averages, pushing up the overall yields.