It's kind of fascinating how the "top tier" ad carries seem to change on their own. It wasn't long ago that Sivir was considered one of the weakest carries in the game, and now multiple people on this thread have listed her as a solid pick, and one of the better carries. No nerfs or buffs to Sivir have come that have justified this shift in position.
Anyway, yea, this definitely weakens Ezreal, but will he still be considered viable? Maybe, but even if he falls out of favor, I wouldn't be surprised if he came back in favor without any new buffs at all.