I am not suggesting remotely religion/christianity is dead in America, it is not remotely. However, it is certainly in general decline.
For Pittsburgh in particular its a multitude of factors, that have caused the rapid shift that is requiring the drastic reallocation of resources. 1) overall attendance is declining... however, this is universal for all denominations nationally. 2) Population distribution.... Overall in the pittsburgh Region the overall decline isn’t what is driving the consolidation as much as folks moving to other areas of the area. The smaller boroughs and towns and neighborhoods of the city have seen classic “white flight” Children of those multi generational Catholic families moved away post steel bust.. and those that did stick around are buying homes out in the suburbs with their families. So, the more densely populated urban core and surrounding neighborhoods do not have the same ethnic or religious makeup they once did. There was a time, not all that long ago, that many of these little boroughs not only were able to support not only a thriving church, but a parochial school as well... and those schools helped many a lower middle income child grow up to escape and move up socio economically because they truly educated their children far superior to the public schools... Now few parishes in that inner ring can support a church, let alone a school... so consolidation is happening... while in the suburbs parishes are growing.
The older smaller parishes are basically dying off, forcing the consolidation.
Basically you are seeing the delayed effects of the 80s and 90s lean times in Pitt playing out.
Plus I did add that the Church is growing in the south as folks head to there.
What I have read is simply a replay of what happened in my diocese ladt year.