Furniture, Wood and Cabinetry Finishing - when to refinish hard wood floors

Is there a point at which hard wood floors must be refinished for their protection? In 1994 we installed hard wood oak floors. I know these should have been refinished after five years but the hassle of moving all our furniture out has kept us from doing it. Now there are a few high traffic areas where I think we are down to bare wood. My wife keeps saying wait til the last kid goes to college (2008). Every time I look at the floor I fear that it will be irreparably damaged. When (if) the floors get refinished, will the sanding process give us a new surface that will not be damaged and so no harm, no foul?

The wood will start looking dull or gray compared to the edges. Some of that can be sanded out, but it is now vulnerable to stains from food, water, pets, etc., some of which can be hard to even sand out. The longer you wait the harder it is to get a new look.
I have a simialr problem, but it is my wife's spraying cat. She bugs me about the floors and I say not until the cat is gone, but some stains are already set deep in the wood.