Just recently I actualy heard what riot wanted her to be, and that was in fact. A non bursting control mage. ( The fact that i never did that already means that they failed in that aspect, but now, after 6 years, they want to force it for some reason)
If this is expected of her, though. I think giving her ult the effect that you can not dash/blink ( all in all, move out of it by any other means than walking) out effect is necessary to do this in a viable way for her. This would put her into the role they want her to be. Sadly, that would be just as unhealty as they claim the burst of her e r to be.
Otherwise, most champions nowadays have some sort of mobility ( or something that will stop you from following/atacking them) implemented in their kit.
The fact that a big amount of champions simply can work around her control abilities ( talon jumping her w now is making this even worse) is making her intended role quite weak in most set ups. You simply do not benefit from it as much as you dit with bursting away your enemy. For zoning you have tanks. For damage you have the adc, mage and bruiser. A mage who is only good in zoning is lacking the ability of the mages who can both zone and deal burst damage.
This whole anivia change looks to me like anivia got the full assasin treatment.
I saw posts naming anivia an assasin with her burst. (completly ignoring that most mages do just that. Veigar dealing 1800 dmg with his r literally oneshot me once. I guess that is okay though, since he does not have any crowdcontrol .... stunned)
She is not an assasin. Not with riots definition. She does not have the mobility of that group of champions. She was the only one I believe who got treated like one, though.