RUNTIME SPECULATIONS: OOTP will be shorter than GoF (that's for sure) so, it will be less than 148 Minutes. It is shorten than PoA also, so it is not of 142 minutes. Remains SOS, and COS both are above 140 mins, so it is expected that this movie will be over 120 mins (that is 101% sure).
Final note- Runtime of OOTP will be between 128 minutes to 140 minutes, 137 minutes suites most.