The problem with that scenario is most times when people are hiking in bear country (especially Grizzly), they aren't just meandering aimlessly looking to view bears or locate bears unless they are hunting them, in which case they have the tool for the job already. Most times they are bow hunting or backpacking, fishing or maybe even hiking a trail for exercise. Many cases a shotgun can not be carried and accessed rapidly enough if a bear does attack. That is why a side arm is typically carried. They are easier to draw and lighter, less bulky. A shotgun is the ideal weapon in a perfect world for defense of a bear attack. IMO, the next best is a carry sidearm that the carrier is very proficient with both fast and accurate. To me as in hunting with a rifle, accuracy Trump's shear power. Find a cartridge that penetrates several inches of skull or main torso and that you are confident drawing and shooting fast and accurate. Be prepared for the worse when in bear country. Nobody ever thinks they'll be a victim of any predator.