What to you think the odds are of Riven getting Alistar or Ryze type changes.
Ali and Ryze got changes because of mechanics that resulted in large disparities between average players and well versed players of those champs, being able to W->Q and knowing how to do the perma-root combo respectively. It ALSO apparently doesn't matter if the change fucks the core of the character either, since machine gun mage was Ryze's whole thing
This is exactly what animation canceling does for Riven, don't know how to do it and she's a trash champ, know how to do it and have run rolling over your opponents. So they could either just get rid of her ending animations effectively auto-canceling like Alistar's new auto-combo, or remove her animation canceling like Ryze 5 seconds of spell spam. Supposedly this will make her "easier to balance". But guess what, that sounds dumb, doesn't it? and they'd never do it because of Riven's popularity. It was just as dumb to do it to Ryze (and Alistar to a lesser extent).