I'm not aware that the basic principles of flight mechanics have changed since 1977, only the amount of computing power available if you want to model it.
In this instance, I opined that windshear primarily affected big aeroplanes, PW opined that it primarily affected smaller aeroplanes - whilst NASA said that it affects all aeroplanes with no particular distinction.
I think that even if they did say it in 1977, NASA probably have the deciding vote in that particular matter - but nobody actually said that windshear didn't affect anything.
That said, there's still no evidence I've seen that windshear conditions existed at the time and place of this accident.
G