@Riot: Immobile Mage Update: What's the Focus?

As we all know, Riot is working on hitting immobile mages next in their recent crusade of champion group balance updates. As someone who loves his non-assassin, immobile mages, I'm curious about this upcoming update. What exactly is the focus here?

It can't be mobility; they are immobile mages afterall. It would detract from their identity if they were gifted mobility.

Complete remakes would take ages with how many immobile mages there are so I doubt that's where that's going.

Simple number changes seems rather shallow and unworthy of a mass update, but could make sense depending.

So Riot, I have to ask: what is the core design focus of this update? With how many mages that could be considered immobile, I find it difficult to imagine any blanket changes to some (or all) of them that could work across the board.

It's been stated before that is up to the plate as the posterboy for this update. Rioters have been insistent that he doesn't feel unique because his only real gift to a team is damage from a distance which isn't unique. Their plan is to rearrange some things and likely change an ability or two so he has something that can be said is "Velkoz's thing."

Could it be differentiation? Many of the mage cast offer some combination of CC, damage, combo power, and poke. With how simple League is, there's not really room for much else so many characters overlap a good bit. Instead of individual champions, it's more that there's certain mage roles that multiple of them fill. How exactly are you planning on splitting champions apart, Riot? Please at least give us a general sense of what's going into this update. I know I'm dying to know.