I saw that too. Considering some of the hidden content in SA, I wouldn't rule it out in DLC. I could be in the game & just
locked (like "Hot Coffee" originally was in SA). Actually, that makes sense, do all the work on the original game & unlock
features every once in a while to look like something new.
I think it will be much harder to hack the game, hopefully there will be a hidden script or code in the game, but R* learnt that the hard way after "Hot Coffee".
The Xbox isn't to blame for anything that isn't in the game, if you wanna flame the 360, go here, this is for discussion about whether there will be changing seasons in the game.