My Parish is packed and thriving with OF and a Latin Mass, we have a good and welcoming family Mass which is always full. Young people attend until they go to University or leave home, it is a very expensive area for anyone starting out in marriage.   The decline happened because more people got divorced, women wanted to decide on whether or not they use birth control, people in their 30s and 40s saw their parents rejected by the church and lost faith, because of the abuse scandals or where brought up by people that were badly hurt by the church, and want nothing to do with it..  I have family who left because they supported a son and brother who is gay, they accept him, not church teaching and they hated their Catholic Schools.  They also had a hard time when a family member committed suicide, being told he was in hell a lot. I don't think EF is attractive outside the US.