In version 1.20 of FFXIV, we will see massive changes to the class system. Abilities will be moved around from one class to another and all classes will lose abilities. This might not sound good at first, however it is something that is needed for class identity. A lot of the abilities currently in the game were simply not being used much and Square Enix felt it best to remove them for now. In patch 1.21 we will see the job system which will bring about further class identity and traditional names such as black mage and white mage.
As part of the changes, there will be more restrictions on which actions can be used on other classes, action cost will be abolished and all traits will be made class-exclusive. A new individual combo system will also be introduced to allow players to chain weapon skills for additional effects.
Since there is a lot of information regarding these changes it would be best to check out the Lodestone forums and read for yourself.
