I had new hardwood flooring installed 18 months ago, one stair nosing got chipped/splintered a little bit, the installer sent out a tech and he sanded it down and it looks fine, but it got me thinking, so I ordered an 8' length of stair nosing, enough for two stairs, for $100. The same flooring might, or might not, be available in 5-10 years, even though the vendor/installer says "guaranteed for life" whatever that means...
I have a box of the flat planking sealed up in an inside closet (humidity and temperature controlled) so I figure $100 is cheap insurance. 5-10 years from now, for $100, I'm happy with protecting my stupid expensive flooring.