- if all bitcoins are mined;
i'm sure there won't be a significant impact here, many say the rewards miners receive come from bitcoins that haven't been mined, but if all the bitcoins are successfully mined, the price will be stuck at the last price bitcoin was at and the miners will still be able to operate, however with other methods cmiiw
- if all bitcoins are lost;
i don't know what exactly will happen next to bitcoin if all of it is lost, but what comes to my mind is that if all of the bitcoin is really lost then bitcoin will become a dead asset and cannot be used at all for transactions (this is just my guess, impossible to experience this because bitcoin will continue to exist even if everything is mined)