I've talked to the founder about that concern before. He said the Sia network is made to function efficiently no matter what the price of a coin is.
According to their FAQ:"Sia is a decentralized cloud storage platform that uses a blockchain to facilitate payments. On Sia you can rent storage, get paid host files, Siacon mine, or contribute to the project! "
"All payments on the network happen in Siacoin"
According to their website with SIA:
Storage Provider: $ 10
Download Bandwidth Cost: $ 5
Clear analysis:Today 1BTC ≃ $ 1761
Today 1SC ≃ $ 0.002498 (0.00000143 btc)
I think this works like all coins. It doesn't matter how much cost 1SC because, for example, Storage Provider costs $ 10.
According to that, if "tomorrow" 1SC = $10, you will pay 1SC.
But today, you will pay 4004 SC, because 1SC is $0.002498
(0.002498 * 4004 = 10). (I think it's correct, please correct me if I'm wrong).
The fact is: When you bought SC and how many people are holding this to increase its value? (of course, coin demand is necessary).
It's the same if SC will be $20, you will pay 0.5 SC (if we follow prev example).
Therefore, it doesn't mean that SC will rise until $10. It means that their rates are in $, and you will pay $10 in SC.
Future:Can SC increase its value? Yes, like other coins.
Limits? No limits, like other coins.
Why? Because it is money, it only has the value that people / trust give to it.
And this is what like me about functional cryptocurrencies: technology that envolves them, because in front of "people" and "trust", coins are sponsored by their own technology.