Yes, 25 years is a long time but Kyocera says they will last that long.......but just in case I bought 3 extra matching panels and keep them as spare parts in my workshop. Aesthetics are important to me. Replacing a 12 year old panel with the latest and greatest might operate OK but most likely will be the wrong size and color. I do not want my arrays to look like a patchwork quilt.
Also I'm 5 years into my 7.5 year payback and right now its looking good to make the system pay for itself. If I have to or want to replace the whole system in 12 years then so be it. Just like most long term investments....some win, some lose......some are better, some are worse.
I do have a unique situation with my "net billing" arrangement. But I believe net billing is the future of residential PV. I can look my neighbor in the eye and tell him he is not subsidizing (through his electric bill anyway) my PV system. We never talk about taxes. lol