If bitcoin will be a success (e.g. 10% of US economy), than i think it will demonetize gold relatively quickly, so gold's price will be around industrial use price. This is the same effect, that happened to silver in 19-20th century.
I don't think gold will ever be demonetized. It's the best physical form of money and the utility of that combined with a need to be diversified means it should always remain valuable as money (short of some kind of cost effective alchemy). Bitcoins or something substantially like bitcoins should take a similar role as gold in the digital world. Government bonds on the other hand are a different matter.
