Yeah, the Church of Scotland is fundamentally unsustainable at the size it currently is. 20 years from now they will need to be about 20% of their current size.

Edit - just found this quote: "In 1982 the Church of Scotland had nearly 920,000 members; last year, that stood at 270,300, a decline of 70%. The average age of its congregants is now 62, and only 60,000 worship in person."