A shotgun is just as useful as it ever was. Id say even more so with advancements in ammunition and good semi auto guns.

If Im out in the wilderness where I might encounter large dangerous animals, it gives me a gun that will take care of that while still being a very effective defensive tool against bad guys.

On the home defense/self defense front it is still the king of close range effectiveness. Ive never seen someone take a good COM hit with buckshot or slugs and still be a threat afterwards. I cant say the same thing with a carbine/rifle. I still use an AR as my preferred defensive weapon and believe it has multiple advantages over the shotgun. But that doesn't take away the fact that a 12 gauge shotgun is a very effective defensive weapon.