Seriously, this is a cultural moment. The demise of the magazine devoted entirely to fondness for felines says a lot about zeitgeist. Niche content doesn’t work when your subject attracts 15 percent of all Web traffic. Instead of instructions for combing Persians, think listicles and lolcats. After 49 years, Cat Fancy is passing the torch to Catster, a new mag more in tune with current appetites for the ironic, outrageous and totally random — like obese cats landing in slow motion. Now that’s purrfect.