It may be well over a year before we even see a Blue Mage, but that's not going to delay my discussion on how I'd like to see one in XIV.
Hopefully this won't turn into another FFXI-2 thread, but here we go....
My preference is to see a Melee Blue Mage, kind of like Kimahri from FFX, but rather someone you would actually put in your party. I'd like for the "Blue Magic" to be TP based and most of them costing 500TP, and 1000TP for the really powerful ones. This way the Blue Mage is able to pull off a series of monster abilities after building up a good amount of TP.
But if Blue Mage turns out to be a Job that is becoming of it's name, a caster, this is what I'd like to see.
A really good MP Drain ability with a low recast. Blue Magic spells with a very short casting time and relatively low MP cost. Cause if Blue Mage plays like CON it's going to be a very boring Job to play.
In whatever shape and form Blue Mage comes, please make it a fast pace Job that can do peak DPS, not a slow casting, MP deprived, "stay on the bench" Job.