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Yes Btc supply as of right now. There will only ever be 21 million supply total.

It will never be 21 million.Many coins are lost because of lost private keys.

Yes if you are talking about circulating supply there will be actually very little due to the fact that many big players hold their Bitcoin, many people lost much of the Bitcoin mined in the early days and the full 21 million will not be mined for a while.

Thanks for the comment :)