I happened to be reading an unofficial English translation of the Holy Father's recent motu proprio. The decree states that the Mass formula of 1962 is permissible and is indeed an 'extraordinary expression' of the same Lex Orandi as espoused by the Roman Missal of Paul VI.
Wouldn't it be nice if the interpretation of 'extraordinary' came to mean the same in practice as that which has applied to 'extraordinary ministers', an instance of where 'extraordinary' has come to mean normal or routine? Maybe it will come about.
Clayton South, Vic