Msgr. Bux has written a letter to Bishop Fellay urging the SSPX to accept the Holy Father's terms for regularization. He pretty much lays it out as we've discussed here many times. Hopefully, calmer heads will prevail and the Society will have the faculties and autonomy to do some good. I think it's pretty clear they've reached their limit with what they are doing now. You can read the whole letter at Rorate, but I highlight the following bit for your consideration at the moment:
It is undeniable that numerous facts of Vatican II and of the period that followed it, related to the human dimension of this event, have represented true calamities and have caused intense pain to many great Churchmen. But God does not allow His Holy Church to reach self-destruction.
We cannot consider the severity of the human factor without having confidence in the divine factor, that is to say, in Providence, who guides history and, in particular, the history of the Church, while respecting human freedom.
The Church is at once a divine institution, divinely protected, and a product of men. Her divine aspect does not deny her human one - personality and freedom - and does not necessarily hinder it; her human aspect, while remaining whole and even compromising, never denies her divine one.
For reasons of Faith, but also due to the confirmations, albeit slow ones, that we are able observe at the historical level, we believe that God has prepared and continues to prepare, throughout these years, men who are worthy of rectifying the errors and the ommissions we all deplore. Holy works already exist, and will appear in still greater numbers, that are isolated ones from the others but that a divine strategy links at a distance and whose actions add up to a well-ordered design, as it miraculously happened at the time of the painful Lutheran rebellion...
The Holy Father's heart trembles: he awaits you anxiously because he loves you, because the Church needs you for a common profession of faith before a world that is each day more secularized and that seems to turn its back to its Creator and Savior hopelessly.
In the full ecclesial communion with the great family that is the Catholic Church, your voice will no longer be stifled, your contribution will be neither ignorable nor ignored, but will be able to bring forth, with that of so many others, abundant fruits which would otherwise go to waste...