What happens to the avatar cycle when the avatar has to be an airbender again or does aang's kid keep having kids that are also airbenders???

I think aang will repopulate the airbender nation. That way there will be an airbender for the next avatar round.

Then the next avatar would be a waterbender and Yes, all people with the airnomad blood running on their veins should be an airbender.. all people in the air temple are airbenders.