With todays technology to support it, bitcoin could possibly be that valuable or somewhat more, it just depends on the speed of adoption.
Ahm and it depends on the rate of reserve and velocity of money. And: In today's dollars or in some hyper inflated USD scenario. Let's assume the latter are the same like today. Same as the economic output.
So what matters is adoption (what % of all transaction volume in purchasing consumer or real investment goods in the world) and rate of reserve (21mio. Bitcoins / all bitcoins and claims of bitcolins used as money).
What is the supply of money worldwide? We have about 1 trillions € as coins and banknotes, 5 trillions as M1. The Euro-zone has about 1/5 of the world economy, so the world's cash should be around 5 trillion and the world's M1 around 25 trillion or 7 trillion and 35 trill.. USD.
So what if there are no claims of Bitcoins (for example people store 1Mio. Bitcoins on coinbase but coinbase has only 500 000 coins over time, because they realise, not all clients want their coins at the same time) and 100% of all transactions are used in Bitcoin?
This would be 35trill. USD / 21mio. Bitcoins = 1.2 mio. per Bitcoin.
So now you can play other szenarios:
Let's assume a 50% reserve rate and 10% transaction volume. This would be 3,5trill. / 42mio. bitcoin = 83 000$
So let's try 10% reserve and 1% transaction volume. This would be 350trill. / 210 mio. Bitcoins = 1650$
What do we have today?
I think it is more or less 100% reserve. Maybe 80%. And the transaction volume should be far less than 0,001% (Attention: The 35trill. USD money supply is not the transaction volume. And pushing around bitcoin from one account to another account of the same person is no transaction volume in this sense. You are not buying anything in and market transaction).
Other effect: If Bitcoin is a better store of value than toady's dollar, this adds value like other features of this currency. If it is more volatile etc. this subtracts value.