SMN could actually get a capstone lv100 OGCD nuke type of skill that's available to use after a full Bahamut and Phoenix rotation. Might be something like a channel Ramuh nuke.

I just see them prioritizing fixing/adding more to SMNs simplicity, by updating current skills and adding a big new flashy skill at lv100. Over adding 3 new summons and keeping SMN as it is.