@ Cutlass
Your writing as if its the Church's responsibility to get young people "involved", rather its the young peoples duty to get themselves involved in the faith and participate themselves in the community. The idea that the Church is there to get you "involved", as if it is there to provide some amusements is simply false. The Church is not there to amuse people, or make them feel good. Furthermore I might add that separating young people from the rest of the parish community is not how its supposed to be either. Indeed all the young Catholics (as in practicing) I know don't need to be accomadated or "included", since an orthodox faith speaks for itself.
Regardless the decline as I said is quite attributable to certain trends that bubbled to the surface in the years after vatican 2. These trends decimated traditional catholic parish and family life within which a Catholic is supposed to live in, and in following the trends of the world the places where this occured (much of the west) made church irrelevant to their children since church simply became something you went too on sunday, and even then you were bombarded with weak sermons and crappy music. Where an orthodox Catholic parish and family life remains however, that is where you see the young people because holiness, real reverent worship, and strong teaching does not go out of fashion like 60's style guitar music, and the families there incorporate the faith into everything they do, ergo its a way of life. Indeed this sort of thing occurs in protestantism as well, where religion is watered down and teaching adulterated those protestant communities are dying, where teaching is strong and firm, and where the worship of God is the focus (compared to the human-centred focus on "community") those groups are stronger.
I recall here the dichotomy I saw in one parish, which had mass both in the extraordinary form and in the ordinary form (latin mass and an english mass). In the english mass there was only one family with children, a number of older folk, and no young adults (save myself) and the church itself was mostly empty. In the latin mass only one hour later the place was filled with young adults and young families and some people had to stand in the back since the pews were full. The attitude was also tangibly different, before the english mass there was chit chat in the church, before the latin mass the entire community was praying the rosary together, and once the mass finished after singing some hymns and praying the prayer of St Michael together everyone before the community went to a place nearby for morning tea.