I'm not quite sure what you mean by "if BTC is to change dollar" but ultimately bitcoin's value is going to be whatever people are willing to pay/trade for it in the markets, which right now is pretty well above zero. 

I have heard of the idea of giving Bitcoin gold backing with some sort of "Bitcoin 2", presumably through another hard fork or altcoin. In fact Doug Casey mentioned something like this in a recent article:

https://www.caseyresearch.com/doug-casey-on-why-bitcoin-could-hit-50000/

But then again, even if bitcoin (or a future version of it) ends up being redeemable for gold, people will still look at the value of gold vs. the dollar, so the perceived value of bitcoin could still have significant fluctuation in terms of dollars.