I don’t actually think that there was any permanent loss, because I do not believe that the actual documents of Vatican II were in any way heretical, or damaging, or ‘took things away’ that should not have been. (That heresies, damage, and wrongly taken things occurred was not the fault of the Council itself).
I do see that because of the actions of some people–clergy and lay–that at least one generation has suffered the loss of the Latin language and the treasury of Gregorian chant. . .but even there, Latin Masses exist and thanks to cheaper and more available music (one can now have vinyl, cassette, CD and beyond) the chants exist as well.
And I believe that those of us who do miss some of the “smells and bells” which were more prevalent prior to Vatican II are going to see them again. And we appreciate them more for having been deprived of them.
And those who appreciate ‘vernacular’ language still have it, and they appreciate the Mass more. That is a great gain for them.
We have the power of choice and we have far more access to information now than was available in 1970. And I have to say that a lot of people who might have been quietly passive and content should the Mass have stayed the way it was have found greater participation and greater and deeper overall understanding of their faith just because they had to work through things which disappointed them, because they worried that they had lost something.
But the core of the Mass is the Eucharist, the Body and Blood of Christ. And that core has not been lost–for many, they’ve come to a deeper and more loving understanding and appreciation of the Mass. . .some through ‘returning’ to the old, some with ‘embracing’ the new, and some taking attributes from both so far as they are able.