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As I understand it Ken (and I may have misremembered it as Uni Physics was about 30 odd years ago), light does "wear out" but doesn't disappear. From what I understand, as light propagates through space (ignoring the reddening effect of dust and gas) it uses up energy. This lost energy reduces the frequency of the light. So if the light at a galaxy on one side of the universe started out as blue, at some point it will become red and then invisible to us as infared and then as radio waves. I don't know the distances and time frames involved but they are considerable.
This is different from the doppler shift of light.
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