The same thing will happen with a gold back crypto as with a gold backed paper currency. The only way crypto can be gold backed is if the crypto token issuer is trusted to only issue crypto tokens sufficient to match the gold held in reserve. The thing is, free market crypto doesn't NEED to be gold backed, which is something the great Peter Schiff doesn't understand. (Schiff hates crypto so never gave it a fair hearing).
There are 2 purposes of currency backing. One is to fix a value to the currency, and the other is to limit the supply of the currency. But free market crypto already has limited supply built into it. Forgery of crypto units or illicit, excess supply isn't possible.
So that leaves the fixed relative value purpose. And that is why crypto dollar prices fluctuate so radically. But that's not really a deal killer for crypto.