According to Thomas Reuters GFMS, roughly 377 MM pounds of gold exist above ground which equates to about 6,000,000,000 ounces of gold. For simplicity, I'll use an undervaluation of gold at $1,000. This means the total value of gold above ground is roughly 6 trillion dollars.
If bitcoin is adopted on a global scale as a deflationary store of value that is coupled with other valuable functions, much in the same respect as gold, what does this mean for the potential price of one BTC? If BTC ever becomes as valuable as gold, we're looking at 6 trillion dollars divided by 21 MM instead of 6 Bn.
~ $285,000.
Is that realistic? In my opinion, probably not. Is it a possiblity? Anything's possible.
EDIT: This would make one satoshi worth $0.00285.