Development of doctrine is to be distinguished from new revelation. The former unquestionably takes place, but there will be no new public revelation that we must consider as an addition to that which we already have in Scripture and Sacred Tradition.
“The Christian economy, therefore, since it is the new and definitive Covenant, will never pass away; and no new public revelation is to be expected before the glorious manifestation of our Lord Jesus Christ.” Yet even if Revelation is already complete, it has not been made completely explicit; it remains for Christian faith gradually to grasp its full significance over the course of the centuries. [CCC §66]
The Church distinguishes between public revelation (as in Scripture and Tradition) and private revelations made to individuals, which do not under any circumstance add to the Deposit of Faith. So for instance the apparition of Our Lady of Fatima is a private revelation; it is “approved” by the Church, but the Church does not consider anything said by the Blessed Virgin there to constitute a supplement to be included in Scripture or Tradition. See for example CCC §67, at the link above.
On the other hand, the Church’s understanding of revelation is not complete. Over the course of time she understands the Faith more clearly. This is rightly and necessarily distinguished from revelation, which it is not; rather, it is the fruit of the Church’s contemplation and increasing comprehension of what God has revealed.
Aquinas, Etc. 
This is a great distinction and you’ve stated it in a more explicit way than it’s usually stated.
Hi Sarah,
Thanks for stopping by, and thanks for your kind words :-)
Many times people mistakenly suppose that a new dogma is a new revelation; others sometimes suppose that things said at Fatima or Lourdes are binding upon all Catholics. Both errors are nicely corrected in these opening paragraphs of the Catechism.
Peace,
Fred
Along these lines, I was recently asked whether Deuteronomy 18, e.g., were still in effect today. This was asked with regard to Anne Catherine Emmerich, John Vianney, et al., some of whose predictions seem not to have come true (according to my interlocutor; I could not pin him down to specifics). What do you think?
Hi Mike,
I know nothing about alleged predictions that have allegedly failed, so I can’t speak to specific cases.
However, with regard to the general principle of Dt. 18, my thought is that it certainly remains in effect in this sense: if a proposed prophet claims that God told him that xyz would happen, and it doesn’t happen, then that proposed prophet is a false prophet and probably a liar in that instance.
I hesitate to say that we may make sweeping, general condemnations. There was at least one genuine prophet of God who made both true and false prophecies; see 1Kings 13 for the details. Consequently I think it’s reasonable to suppose that any particular person might make genuine, divinely-given prophecies (known by the fact that they come true) but might also on some occasion lie (or at the very least be badly deceived, but I don’t pretend to know the mechanics of receiving prophecy from God!).
In any case, however, it is indisputable that public revelation has ceased, so that even if a predictive prophecy was given any accompanying declarations would have no force for us generally, but would be only private revelations that are binding (as the Church teaches) for those who received them.
That and an embarrassingly large wad of dollar bills can get you a pretty good cup of coffee. :-)
Fred