Most bags do not wear out. They get neglected, then wear out. Coated nylon in particular fails from things that are easy to avoid.
Rinse the salt and grit off
Road salt and fine grit act like sandpaper on a coated face fabric. A rinse with clean water and a soft cloth after a bad week does more for the bag than any conditioner.
Never put it in the machine
A washing machine will delaminate the coating and destroy any taped seam. Spot clean with lukewarm water and a little mild soap, then rinse the soap out completely.
Dry it open and out of the sun
Hang it upside down with every compartment unzipped. Direct sun and radiators both cook the coating and make it brittle.
Look after the zips
Zips fail more often than fabric. Brush the teeth clean, and if a slider starts catching, a little wax on the teeth will usually fix it before it becomes a repair.
Store it with room
Do not compress a coated bag flat under other things for months. Creases in a coating become cracks, and cracks are where water gets in.