[ultima ratio]

Your statement suggests two caveats:

First, the Council made it very clear that while doctrines legitimately develop over time, they can never evolve into their opposite: "Hence, also that understanding of sacred dogmas must be perpetually maintained...There must never be a recession from that meaning under the pretext of a deeper understanding." (Vat. Council I, canon 3.)

Second, "ex cathedra" can never be assumed as you suggest. "Ex cathedra" applies only to the most solemn of papal pronouncements and involves an intention to bind the universal Church. Hence it requires the kind of promulgation that leaves no room for doubt or equivocation on the part of theologians. It is extremely rare.

[saradippity]

Yes. There is a document,I think a Moto Proprio,issued by Ratzinger in the late nineties that elaborates on this. It says what the document you quoted says,as well as what I said. It just reiterates what Catholics must hold to be true based on degrees of "definitiveness",written in a style that is more conducive to comprehension by the majority of average Catholics.

It is so clear that the liberal media,Catholic and secular,and the progressive/modernist Amchurchians buried it. A good divisive free-for-all is what they pray for,if they can divide Catholics than they can continue putting into place their plan for us,all of Christianity and Western Civilization.