For those that have been healing in this game since at least 2.0 we all understand how the game and role work and flow as time goes on. In the early days of 2.0 when everyone was running in their item level 50 AF gear, healing was hard and scary. The tanks would have their HP drop down to a sliver in an instant. It was necessary to be on your toes, memorize the tank busters, prepare mitigation and precast heals. Then we all gear up, the expansion gets older and all of the content gets easier. As things get easier for a healer we have less and less to do during a dungeon or raid and so it becomes increasingly more important to start doing DPS instead of standing around and twiddling your thumbs. Even at times with raid content early on as a scholar I would probably spend 80% of my time doing DPS instead of healing.
Despite the changes the same will undoubtedly hold true for 4.0. Even now healers still have plenty of down time where they are capable of doing DPS as they do not need to heal.
But now we have something very different in the game.... The Red Mage. I made the transition from long time scholar main to a red mage this expansion and all I can say is that I am blown away by the healing potency and speed of vercure and verraise. While many speculated repeatedly casting verraise would deplete your MP and render you useless I can say from experience the red mage requires very little MP and can recover a significant amount with lucid dreaming to a point where this is a non issue. The biggest drawbacks to a red mage's ability to heal would be the lack of an AoE heal and an Esuna although we do have a role ability that can cure a DoT every 90 seconds.
So what does this mean for healers? I can say that as time goes on and content ages I would not be surprised in the least to see the red mage replacing the slot for a healer. What would you rather have in your party? A healer that spends 80% of their time doing DPS or a DD that spends 20% of their time healing? If content is doable with a red mage instead of a healer then the choice seems obvious.