In my scenario, the iOS Gold Master would be released after the 27th announcement.You're missing one thing. The GM CAN'T come out BEFORE the Media event, because it will contain features for the new iPhone 5. So either the Media event is BEFORE the GM or on the same day!
Apple controls the entire timeline; they can easily push the release of the iOS Gold Master back a week. After all, they've already moved the iPhone hardware release back a couple of months.
About the only thing that Apple can't control is the holiday sales season. That affects the iPod product line more than other product lines though (iPod sales in the holiday quarter are approximately double of any other quarter). Still there is plenty of time for Apple to have everything released before we head into November.