The amount is denoted in USD so the markets would determine the amount of Storj which represents this.
The other main factors which would lead to the price :

• amount of storage provided for use
• The cost to store which decreases with advancements in technology
• The network cost which will fall as the network grows
• The security of the network, which increase with growth and further distribution

As far as I know there are no limitations on the network size so long as the services provided to assist operation and payment are at a scale to meet demand at the time.