It will either be 0 or an insanely high number (think trillions)
It's the only way it can be really
If Bitcoin survives until then, it must be very well known and widely adopted. It will be the world reserve currency. So the price will be high.
Honestly I hope it will survive, but I don't think so. The model can't be sustained for this long of a period. Either their will be a new age crypto coin.
Or some other new innovative thing. Or the World will be not more...