Their fur won't be effective camouflage once the ice is gone, but they're still be successful predators, with pounds of muscle, sharp claws and teeth. They already know how to fish. Some will die out, sure, but some will also adapt and overcome. Such is the nature of life. It is the pinnacle of human arrogance that asserts that was is must always be, and that the Earth must forever remain in the state we have become accustomed to.