There's no way they are going to back off on this because they have been advertising it in the game via the MOTD status messages. If they suddenly decided not to do it, the backlash from entitled online gamers would be legendary.

Having said that, Rockstar giving everyone $500k GTA$ is pretty much a non-event in the face of the fact that they will be selling GTA$ for real money. The $500k of GTA$ money they are giving away will be purchasable for 10 bucks in as many $500k increments as you wish to buy. And while in the case of buying the money outright you can more easily choose to not participate, the fact that tons of other people will participate (I've seen people waste ridiculous amounts of money on COD Black Ops 2 "camos" for example, things that don't even give them an in-game advantage the way money does in GTA V Online) will already make the overall game economy incredibly loopy.

If you really don't want the free money, when it appears in your bank account just use it to put super high bounties on random people. You'll burn through the money nearly instantly with nothing personal to show for it and cause epic havoc on the server you're on at the same time, which is very much in the spirit of GTA.