I had a gut feeling the DLC wouldn't be coming out the day exclusivity ended. Business is business and I accept that fact. Games are difficult to create and market; I also accept that fact. Unfortunately as time passes most folks will have spent so much energy tracking the release date for Dawnguard on PS3/PC that interest will wane. My interest was at a peak last month on June 26th. My interest today is minimal, as I'm sure others are approaching.
Release it whenever. I may or may not purchase it based on my disinterest.
I have plenty of other games and by the time Dawnguard makes it to PS3 my thrill for another questline may be fizzled, much like a failed shout attempt on cool-down.