One day all of the 21 million bitcoins will be mined but ending of bitcoin is not a thing. Bitcoin is making steady growth and have largest trading volume day by day. So i don't think bitcoin is going to end.
Well bitcoin can't really be end unless the community of bitcoin itself doesn't want it to be ended. Even if two people are using bitcoin it will still occur. But it value will decline greatly. With each person adapting to the community of bitcoin the changes of destruction get lower & similarly with each person leaving the community the chances get higher & banning bitcoin will never stop this coin from progressing example is Chinese ban.