They don't need to completely overhaul the job like many suggesting, but they have an opportunity to change them a lot now with new abilities and traits coming in 3.0...
The new abilities could bring some more burst damage (not too much, cause there needs to be some difference between BLM and SMN), and either with that burst, or with another ability, they could make the job more interesting... They could make one or more abilities that is tied to the primals that was gonna be used with SMN, not new egis, but abilities that call upon those primals and perform an attack of some sort. The possibilities are unless.
One of the traits could fix their MP issues further (still needs some work considering BLMs advantages IMO), if that's even needed with the level increase and whatnot...
In other words, they could completely change SMN around without changing abilities that are already in the game. Might not please everyone, but I would go back to SMN in a heartbeat if they just make them balanced and a little more exciting than ruin/ruin II...