In the aftermath of the changes there was a falling away. I know of many families and individuals who just walked out. They didn't go anywhere else. Some gave up any expression of the faith others just stayed at home and said their prayers. One small group continued to meet on Sundays to say the rosary and make a corporate 'spiritual' communion. I suspect the alternatives available were not to their taste for various reasons. They still believed in the Church but couldn't tally what was going around them with what they had been brought up with. The universality of the Church had been key to their understanding of what it meant to be Catholic.
In the last three years there's been a steady stream of people quietly coming back- not with great announcements- but just gently slipping back into the practice of the faith. Their 'first contact' has often been the discovery of the Mass as they remembered it being celebrated in their local Church. We won't know the actual numbers- there's no way of quantifying what is a private matter. For this fruit we should, quietly, give thanks.