Re: Dr. Chang recognizing Hurley
It's entirely possible, yes, if the flash-sideways universe was created by Juliet detonating Jughead at the same moment the island time-traveled. This means everything after that point in 1977 changed.
Alternatively, if the flash-sideways universe exists because of what our people are doing in the "real" universe to stop the Man in Black, it's entirely possible that Chang never met Jack, Hurley, Kate, Miles, Sawyer, etc back in the '70s as that timeline did not occur in Flash-Sideways-Chang's timeline.
Thirdly, perhaps Chang is well aware of the "real" universe vs. the Flash-Sideways-Universe the same way Eloise was?