If it will be like bitcoin cash thend I don't think bitcoin gold is going to be a failure. Bitcoin cash has performed very well if you look at the way many traders has speculated it to be. Many has said bitcoin cash is going to die before the end of August but uptill now its market capitalization is still above  $5b, according to the data from https://coinmarketcap.com. Bitcoin gold may be different a little because of the  ideas behind both of them. We all know that bitcoin core has out perform all of them and will ever remain the face of cryptocurrencies because of the ideas of satoshi and the structure it has developed so far.