I know it's a big "if", but if they follow the road map, P3 should last 1 to 3 weeks, followed by a 1-2 weeks "debug phase" and a 1-2 weeks P4/OB. That's 3 to 7 weeks. I guess it's safe to assume 7 weeks, but that's still hardly september.
Either way, really happy they announce the release date soon enough so we know where to stand.
I'll be surprised if phase 3 lasts anything less than 4 weeks. 2 week gap, 2 weeks phase 4 and most likely a 2 week gap between phase 4 and launch. Mid August sounds most likely, which is shitty because many people take holidays in that month. I've got a 5 day one planned and I just know the release date will be the day I go because that's how shit works.
PS3 LIMITATIONS BRO!
I think the biggest thing they gonna focus on from now on is the combat system. Crafting/gathering are good as they are and everything else is just filling in the blanks with content so I don't see where else they could get any huge delays. Shit like bestiary, etc, can be easily added in the patches.