After hitting level 50 and learning all 49 spells, I believe I can safely say that Blue Mage as a job has the basic skeleton there. There IS a rotation, it uses a good amount of your 24 spells, and it's balanced, slightly underpowered at worst, against other jobs relative to level 50 or so. There's a few problem spells (white wind, maybe peculiar light) that may need to be tuned or have differing/reduced party effects, but I believe the easiest solution going forward for removing many of the restrictions of Blue Mage is to simply allow some spells to only be used in unsycned instances and Masked Carnivale. The suicides, instant kills, etc. This would not "break" unsynced content any more than it already is by virtue of it being unsynced.
It's either that, or, by actually using more dev time and resources, listen to the other half of suggestions and change some overworld design, fight mechanics, stat weights, etc. and make them overpowered and broken enough to actually solo primals and such by themselves as people thought was advertised.
Either way, whether Blue Mage dies off, the content schedule for it remains repeats of this iteration, they listen to fan feedback, what have you, it's my understanding that the vast majority might all agree on at least 5 points:
1. Give Blue Mage a limit break.
2. Allow Blue Mage to access dungeons w/ squadrons.
3. Allow Blue Mage to access various content upon their level 60 cap, such as Palace of the Dead, maps, etc.
4. Develop a PvP Blue Mage.
5. Reduce the amount of spells that require being carried through content.
My personal hope is of course that they manage to incorporate feedback from the players and remove many of the restrictions each subsequent level cap, but at the least I think these 5 points are shared by a majority of the playerbase at this point.