That's a valid concern, but it also assumes that the requirements for apps will go up in a similar trend as they did in the previous 8-10 years.
I'm not entirely convinced that they will. Smartphones 10 years ago were still very much a developing product category, whereas I think today they are generally matured.

Just look at laptops as a comparison. When they were still rapidly developing, an eight year old laptop would have pretty much been obsolete. But today an eight year old laptop will still serve most people perfectly fine.