Never. This is impossible
Although it is really hard to believe that Bitcoin can cost a million, it might happen. However, many years will pass, and for this only a few BTC should be remained.
By hard, that means there could be a possibility, but may be hard to achieve. However, this is an impossible thing to achieve at all this year. In the long run, however, no one knows but it can be possible since everything balls down to demand and in that case, there must have been a serious huge level of adoption but when it will be is what no one can actually tell.