One thing, though, is that the question was asking if model building will die out...
Let's not forget that includes military, aircraft, model ships, etc., which have pretty enthusiastic hobbyists, although I don't know how their numbers might compare to model car builders.
Those subjects also make up a huge part of the catalogues of companies like Revell, etc., and may have something to do with their overall budgets regarding how many new car kits they issue.