Different approaches for different people. Up to this point, I've generally only used a PSU for 5-7 years. However, prior to the last few years I never bought the high-end models, some which come with warranties for up to 12 years. If they manufacturer is confident enough to offer such a warranty, I'll probably ride it out until then.
One thing I am interested to see how it plays out over the next 5-10 years or so, is if many of the PSUs that feature a "fan stop" type of feature will fail well short of their warranty lengths. So many new cases with PSU shrouds force people to install their PSUs with the fan facing downward, and if the fan doesn't run very often, the heat will rise and pretty much sit inside the PSU housing. I know that the manuals for my G2, G3, and Seasonic PSUs state the preferred install method is with the fan facing upward into the case, or otherwise disable the fans from stopping if the only install option is facing downward. I imagine quite a few people disregard this. At least with most manufacturers they have a button that disables the "fan stop" feature, unlike the higher-end units Corsair offers.
I could be totally wrong, but it will be interesting to see how it plays out.