Hackers will just adapt with daily client release. Too much disruption for too little gain.
Yes and no. A small handful of hackers who actually know hacking, will be able to update their clients, but the majority of players who cheat, those who rely on client releases, will be left without a way to cheat, unless they rely on daily released clients, which would only work for so many hours, and would be highly prone to infected clients due to the high demand and short span of checking clients. The disruption can be countered by a game launcher for those who use the vanilla client. Steam would update itself, and the web page hosting realm could simply update (if they do use the path of web unity support).