The Episcopal church is less than half of what it was over 100 years ago, the same cannot be said of the Catholic church.
But you are right there have been mass defections because the faith was abandoned after the confusion and rot of the misapplication of VII by CINO shepherds, teachers, catechists, social justice for all but the unborn type people.
Factually where you will find a huge increase in young people is in the traditionalist movements where the faith is still taught in full, the sacraments celebrated, devotions upheld and right worship enacted. as a matter of fact the largest seminary in the USA was recently opened in Virginia and it doesn't belong to any Novus Ordo religious group but to the SSPX. Also as a matter of fact, the largest segment of growth within the dying Catholic church in France is the traditionalist movement with the number of ordinations surpassing the total of all the French dioceses ordinations.