From 2099 till 2140 (when the last satoshis will be mined) there will only be one bitcoin mined. By the end of the century, supply is virtually fixed and limited to the maximum of 21 million. For the following forty years, miners will be mining only one bitcoin...
The supply of bitcoin is fixed upto 21 million and after halving the mining rewarda get half as now it has reduced to 6.5 per block mined.And we are talking about the time which is very long to come and by that time the prices may be too high that miners will be interested in mining one bitcoin also and about the production cost of btc like electricity prices at the moment.So it depends upon time and current situations of that time but btc will always provide freedom to user for transactions in coming time and its the revolutionary digital currency of future.