My hardwood floors have been there since 1949 and have survived, fire, flood, dogs, cats, children and me.
1929 here. Fire did destroy one room's floor, never had a true flood, but have had plenty of water drip from bathrooms on the floor above. Many children have been through this house before I owned it, and two are in it now. The hardwood looks great.
As for removing the one bad board without damaging the surrounding boards. There are many ways to accomplish this, but a Fein tool makes short work of it.
Yes, you can replace a single board, or a section. But getting it to match perfectly may be difficult unless the wood already has a lot of natural variation (not really seen in today's flooring), or you have extra pieces. Same thing goes for any stain you use. Put the can away somewhere.
But it takes something really bad to damage a hardwood floor board to the point that it needs replacing. In all honesty, every hardwood floor board that I've seen replaced was done when someone bought a house, ripped up the carpeting that covered the hardwood, went to refinish the hardwood and wanted to remove the stains where a pet had peed in some corner of the carpet and soaked the flooring beneath. OR, when huge cast iron steam radiators were removed to replace with hot water heat, and large holes had to be fixed (but that's usually solved with plugs and filler).
Never actually seen a board needing replacement from physical damage.
