That's not in the original approved message. It comes from later version written in 1879, which was placed on the Index. Here is the original, approved message of LaSallette:
Nothing about Rome losing the faith and becoming the seat of Antichrist, or about the Church being eclipsed, in the original approved message.
No, but Cardinal Ciappi, who read the Third Secret, stated that it refers to an apostasy that begins at the top. Padre Pio told Father Amorth that the Third Secret deals with the infiltration of the Church by Masonry (such as the Sons of Italy ... hmmm) and the establishment of a Counter Church. Sister Lucy said that the Secret had to be revealed by about 1960 because it would become much clearer then. We know that the Masons have openly stated that their goal was the takeover of the papacy, where Pope Leo XIII saw this in his famous vision, referring in his subsequent extended Exorcism prayer to the Masons attempts to take over the papacy, etc. Catholic prophecy is filled with predictions of an Antipope, a Counter Church, an Eclipse of the Church, an Apostasy ... followed by a subsequent restoration of the Church. When we see the destruction that has resulted directly from Vatican II, only an idiot or someone of bad will cannot connect the dots here. Which one are you?