Indirectly, this is sort of about home repair.

What is a good, workable approximation of the useable lifespan of a mobile
home, either single or doublewide? 5yrs? 10yrs? 20yrs? Other?

I'm looking at options for a small vacation place on a lake, and am
considering all kinds of construction for cost comparisons. Replacement
cost has to be factored into the picture, and that is dependent on
lifespan.