When I visited the US I had the opportunity to fly on jetBlue, and wow! Service was great, fleet was new. Plus they gave complimentary snacks & drinks, and provided free satellite TV!
The reason they haven't ordered these already is that they are too small for Iceland air who need the larger aircraft as they operate lower frequencies.
Unless they're able to position themselves as the Emirates of Northern Europe, it seems like the 737 MAX is their best choice to replace the aging 757 fleet. Who knows maybe we'll see a row of 77Ws and A380s at KEF one day!