Bitcoin wasn't designed to replace gold; it was designed to replace fiat currencies.  There is a marked distinction.  In the long term, bitcoin should stand on its own, but in the short term -- during the transition period -- bitcoin will  be attached to a known value, such as gold, whether you like it or not.  It's the market at work.  Today, it is attached to myriad fiat currencies.  This works, for now.  But it cannot last.