A: Although a clarifying instruction on several such questions was frequently described as "imminent," a long time has passed and it would seem that it is still in the pipeline.
All the same, it is important to remember that, even in the ordinary form, the use of female altar servers is in virtue of a specific permission and is not automatic. As the Holy See has explained on several occasions, the local bishop may permit the use of female servers but may not oblige the pastor to use them.
Also, the Holy Father's motu proprio granting permission for the celebrations of the extraordinary form was for the Roman Missal according to the edition issued under Pope John XXIII. Since the rubrics of this missal in no way contemplate the possibility of female servers, then it must be surmised that only altar boys or adult men are allowed as servers in the extraordinary form of the Roman rite.