What the writer is missing is the symbiotic relationship of Ubuntu and Debian. Debian does many things really really well. Somethings, like frequent releases, not so well. But for those of us who use Debian, that would be a beautiful design on top of the cake and frosting we already have... Without it, that cake tastes pretty darn good.
Ubuntu came along and tackled this problem, so Debian can continue doing what it does best. To top it off, Ubuntu has funding. And they aren't greedy leeches who take Debian's hard work and exploit it as their own distribution. They contribute back much of their work to Debian (if the Debian developers like the changes). With Debian, Ubuntu wouldn't survive. Ubuntu's funding and hard work ends up helping Debian.
So about saying "Debian will hit a brick wall"... I would ask the question, did you close your mind and hit a brick wall?
Our perception of a situation is based on our experiences and our knowledge of the situation. If we are missing information, our perception about the situation may be off. Like the fact I haven't read the actual article this is about... I'm probably missing something.
Two is not equal to three, even for large values of two.