When the Bitcoin will reach its limit.
And it continued to grow, you think the price of Bitcoin will increase?
I am not sure what is going to happen maybe they will expand and make some more Bitcoins but that means that the value also has to go down if there are going up the limit.
Or they would divide it up into smaller and smaller denominations. It'll be rare to see one whole bitcoin in someone's wallet at that time.
Anyways, we still have more than a hundred years before that happens. I'm sure we'll have a solution at that time.