I was actually giving my two cents on why certain mages were picked for updates over others. I have no information on how the item changes will affect certain champions, but I don't think it will be as drastic as people think.
I've been playing with minimal mana regen builds over the last couple of weeks and having a butt load of mana + the meditation mastery doesn't feel any different then having infinite mana due to mana regen. The thing that will change is that you will eventually run out of mana if you aren't careful which will add another layer of mastery for playing a champion and create more fun encounters.
In addition it will define the good mage players from the average or poor mage players with their ability to manage their resources and know the limits of their champions. I also have no doubt in my mind that if certain champions just aren't playable due to item changes that Riot will address them in the coming patches, or just hotfix it if it is bad.
TLDR:
Was commenting on my opinion for which champions got picked for this update over others. Mage item update doesn't look that bad, just different, doubt it will break the game.