1)  POF Step Index Fiber (this is the quality we use) is used since years in Automotive. In Europe there are around 20 Mio. cars already equipped with POF networks (they use 20Mbs MOST System).
The specification here is min. 20 years operation

2) Mitsubishi Rayon has made a computer based calculation about the life time (the presentation has been given at the POF Conference 2006 in Nuremberg)  and stopped the simulation at 100 years.

This should be enough.

3) My first prototype with POF I have made in 2000 (it was a prototype media converter from Sony) and I have installed this cable in 2001, it is still working perfectly.

I have no doubt that POF is a reliable long life medium. But it is important that it is a quality polymer optical material, of which I know 3 main supplier in the world. (Mitsubishi, Toray, Asahi )