Yes sooner or later Bitcoin will exceed the market cap. of gold but here the fun part begins... Gold supply is not limited it is estimated 2,500-3,000 tonnes annually however, bitcoin is limited to 21 millions bitcoins only.
Probably later than sooner though, because gold is really really slowing down now and since last year banks were buying back all the gold from customers. I read that even in Germany banks were forcing customers to sell back gold and silver to the banks,,, so I think we will see price there grow as much as Bitcoin. For the next 10/20 years.