To be fair, we can't really go on preview information anymore. Those previews were in May, 4 months ago. In the very first previews in November 2012, properties weren't in AT ALL. So obviously things like this are subject to change especially since they have put a heavy focus on GTA Online.
Properties = Businesses (not safehouses) which give a weekly income and some are storage (garage, helipad, marina etc)
Safehouses = Not purchasable as confirmed by Rockstar's comment, but they might be given as we progress. Check below screenshot for example; Chop is there, so looks like a safehouse?
Real estate = MIGHT be GTA Online exclusive, since the world will be dynamic and they said apartments are part of the world where your friends can visit. Or, we are taking it the wrong way and it is actually a business (way to earn income by buying/selling like stocks) rather than physical homes we can enter, but will be unlocked later in the game.
Really, if I've interpreted correctly then it isn't too bad. If we get better safehouses as we progress I'm OK with that, since a lot of the properties are garages and stuff and that's all we need them for.