Since Appa is the last of his kind, when he dies does that mean that sky বাইসন are officially gone? :'(

Nope. It's revealed in the Legend of Korra that they found a whole herd of হারিয়ে গেছে Sky Bisons. So his species lived on!

Well he would yea but they found a whole island of বাইসন so his rce should be ok

Soo sad hes his last kind.I'm curious does anyone wish they one

Nope! Aang's airbending son (sorry I can't remember his name...) and his family have a sky-byson called Oogey (I think.)!

Well, in the Legand of Kora it shows a lot of sky বাইসন (and baby sky বাইসন that are really cute) so I'm assuming Appa was able to find a mate.