The value of the coin at any one time is determined by its popularity (driven by coin features and/or marketing) the number of coins on the market at the time, and the difficult in obtaining the coin through mining (driven by mining hardware to obtain a reasonable amount of coin in reasonable amount time). Total coins matter -- but it is not the only piece of the puzzle.
Especially considering that this is 50-75 years in the future.. If bitcoin was invented in 1939 or 1964, would there really not be a better alternative in 2014? I can't imagine what the world is going to look like in 2064 or 2089, but I imagine they will be laughing at our 'primitive' means of exchanging value. And this technology is cutting edge right now.