I have several of these, IME they remain attractive looking in dry indoor conditions for at least 10 years, after which they still work just as well but look a bit tatty.

I recently found one of these lanterns that I had forgotten about for 25 years, it was still shiny and new looking, but it was still stored in the original heavy paper wrapping which I presume is impregnated with some preservative material.

I prefer these lanterns to the Dietz ones due to the lesser size and weight.
Here in the UK Fuerhand lanterns, made AFAIK in Germany are more readily available than the American Dietz lanterns.

IMHO, an important part of preparing is not only to keep a number of these lanterns and fuel to hand, but also to equip ones home with suitable hooks or brackets from which a lit lantern may be hung, safely away from children, pets, or accidents.

(yes I know that this is an old thread, but the points raised are still as relevant today)