By quoting "usque ad consummationem saeculi", the Vatican Council authoritatively interprets these words of Our Lord to refer to his presence by means of the shepherds.
It doesn't.
The Vatican council says that Our Lord promised to be with the militant Church "omnibus diebus usque ad consummationem saeculi" (all days until the consummation of the world) in
Dei Filius and that "ita in Ecclesia sua Pastores et Doctores usque ad consummationem saeculi esse voluit" (it was his will that there be shepherds and teachers in his Church until the consummation of the world) in
Pastor aeternus.
This obviously refers to Mt 28,20. There is no other promise of Our Lord this could refer to. I don't understand why you disagree.
It just means that the hierarchy will also always be with us just as Christ will be.
Yes, but to be more specific: All days until the consummation of the world. Why do you crop the clear words of Our Lord and of the Vatican Council to "always", which is a disfiguration? Why would anyone want to accept your words and reject the words of Our Lord and his Church?
To say that usque ad consummationem saeculi means until, and not including, the consummation means that Christ would abandon us during the consummation.
It means that in Mt 28,20 Christ did promise his presence until the consummation, and that he did not promise his presence during the consummation. And yes, insofar as shepherds and teachers are not promised for the time span of the consummation, one would or could expect to be without such during that period.
There's no way around that, the same phrase is used in both Vatican I's promise and Christ's promise.
Yes indeed. But, not promising his presence by means of his shepherds during the consummation, does not mean that the sheep are abandoned. There is e.g. the Paraclet. On the other hand, as prophecised by Daniel and by Our Lord himself, a great tribulation will make things very difficult, even for the elect.
https://w2.vatican.va/content/pius-ix/la/docuмents/constitutio-dogmatica-dei-filius-24-aprilis-1870.html
https://w2.vatican.va/content/pius-ix/la/docuмents/constitutio-dogmatica-pastor-aeternus-18-iulii-1870.html