We've been using our JBL system for probably 5-6 years now. Nothing has yet to fail, although we did take a couple of the PRXs into the shop because they were getting a bit noisy. But we've never had a speaker fail at a gig. Should that happen, we carry around some Eons in the trailer for various purposes (satellite systems and such) and could always throw up one of those to get by with for a night. Losing a sub would be a bit more problematic, although that's yet to happen either. But I'd like to get a couple more anyway. In which case losing one would be less of a problem.
I also have a pair of Yamaha powered speakers I used for my keyboard speakers for about 10 years--although now they are pretty much retired since we went to IEMs. Except for one blown horn (still not sure how that happened), those have never failed either.