When I see 11 and 12 year old kids wearing a brand, it definitely spoils it for me. The same when I see older(45+) people rockin another brand -- it kills it.
The only way you can stay consistent and become an everlasting brand is by keeping it simple, i.e. look at POLO, Lacoste, Ralph Lauren blah, blah, blah -- simple and timeless designs. It may not be what the "streetwearing" crowd wants, but I bet they are going to be here way past my time.