Why do you believe that a PSN game (marked as being a downloadable title for the PS3) will work on the PS4? Where did you form that expectation?
I wouldn't be surprised if they used Gaikai to stream something to you, but do you think that this was actually supposed to happen? If you bought the same game on disk for Box A, why do you assume it'll work on Box B?
Cause it's an expectation most consumers have these days. Why does iPhone 3GS apps work on iPhone 5. Why do most of my software from Windows Vista work on Windows 8.