I cannot deny that what you observe is true.......that the evidence of the "decay" is not "everywhere - to use your terms.
But please follow me on this........what you are observing does not show the whole picture. Adn I should note that I have seen both aspects of it in different parts of the country.
Let me cite the example of the Archdiocese of NY. Nobody can deny the white flight which has occurred in the urban center for some 40 years. Parishes in formerly working & middle classe nsighborhoods which had thousands in the pews in the 60s, now have congregations of 300. Why?
Because the congregation has either died off or moved to the suburbs which surround NYC. The suburban churches are full on Sundays - many of the Urban ones are not. But this is not for lack of people living in the urban centers......rather it is because they are non-believers....unchurched. They do not believe in anything - except their wallets and genitals. They are not interested in Christ, and the Catholic clergy have shown no interest in converting them.
So, the urban churches grow empty as their congregations have left, and have not been replaced - by anybody. The huge influx of illegal immigrants from traditionally Catholic countries has not helped - except in a few parishes. Most of these peoples simply do not go to mass. Those who do will be a temporary phenomenon, as they will not populate the neighbodhood for a generation or more, as did other ethnic groups.
Now, let's go to your suburban churches. They are populated by those who have fled the older urban areas - either to raise families, or to retire. The latter group is currently (and rapidly) dying off. The former group will not grwo to any great degree.......due to a lowered white birthrate due to late marriage, abortion, and contraception.
And as to their children? We all know that the overwhelming majority of young kids do not go to church (unless dragged by mom & dad) much after Confirmation. Additionally, suburbs are transitory in nature. The youth will grow up, leave the homw, and 90% will not return to dwell in the neighbodhood where they were raised.
So, what you are observing are aspects of a temporary phenomena. The congreagtions of the NO churches - all over - will continue to shrink, if "these shadows go unaltered".
I'll quibble only with you saying "The congreagtions of the NO churches - all over - will continue to shrink" because you qualified it with "NO." There is no such church as the No Church. There is only the Church. Calling it the "NO Church" is professing a schism which does not exist. SSPX Is not a basis for qualifying that statement, not because they are schismatic, but because they are insignificant in size to justify qualifying the "Church" with the adjective "NO."
Yes, SSPX has grown. Protestants have witnessed 1000 times when an insignificantly small new denomination starts up, it's growth looks impressive. The act that there are 200 million people who are more comfortable with Latin Mass, and the SSPX has brought over several thousand of them does not impress me that the SSPX is the future of the Church.