I visited the magnificent and TRULY awesome Koln Cathedral in 1987.
Even back then it was more a museum than an active Church.
Sad.
But hopefully not for long. The Catholic Church is ancient and in Her long history, She has seen many spells of empty and cold secularism before.
In 1977, I travelled around France, Germany, Belgium and Switzerland to visit a number of Gothic cathedrals, including Koln, Amiens, Rheims, Notre Dame (Paris), St. Michael & St. Gudule (Brussels), and the Munster (Berne). Even back then they seemed like museums, except to the elderly folks.