SMN doesn't need to be rebuilt and it's not something that will happen anyway. They just need to improve on what it was built on.

I only expect adjustments to SMN's existing skills in 4.x so I just hope they actually fix its problems in the coming patch, which is the clunkiness, how limited the AoE is and how punishing it is to die compared to other jobs.

In the future expansion they should improve on the Demi-summoning aspect of the job and actually give them new (and useful) skills.