How would this even work? you cant peg Bitcoin two Gold, they work differently ..
Probably the same way gold ETFs do.
Who would pay for the block rewards of the miners? As it stands now, the network derives it's value from the security of the network, so when a miner finds a block, keeping the network secure, "the network" rewards the miners in the amount of 25 BTC. However if bitcoin got it's value from gold then the fact that the network is secure would add little additional value to the network and the miners would have no way of getting rewarded