Predictions of their demise can be wishful thinking.
Congregations reflect the catchment area that they are from. A part of town with a lot of retirees in it will make an old congregation. The next one from an area of town with the sort of housing for families will have a lot of kids. It can also be cyclical. Todays children will in a few years be a congo full of teenagers. .. then they grow up and move . That's life