TERA a bull, quoted for reference. As far as $20,000 goes, I think that is a very, very low goal if we look 3-4 years in the future. The USD is going to hell, central banking countries are going bankrupt and when the shit hits the fan, I know exactly what type of currency will take center stage.
Bitcoin will probably become worthless once people can't even afford internet access or devices and service providers shut down. Before that phase, people wil be dumping as much btc as possible so they can buy survival supplies and metals.
The commodities you named make poor money, because they are burdensome, short lived, have not enough high supply/demand ratio (gold is at 70 years now, silver 15 years, oil a lot less than a year).
Bitcoin have a S/demand around infinity (because the demand for consumption is practically zero).
Make peace with your mind, even if civilization took a step back of 200 years (like 1815 - Napoleon was just around) there would be world commerce and with it the need of technology.
It cost less to bring stuff from Shanghai to San Francisca than to bring stuff from New York to San Francisco (or Chicago).