I don't think anything you have said is wrong. Actually, I think you may have highlighted something unintentionally, being that if there is a correlation between the supply of Bitcoin and the supply of gold nearly being exactly a factor of 10. Very interesting!

As for price predictions, you have a good argument with gold against BTC. The only missing component that might limit the highlighted potential of up to 600k USD (at current gold prices) is the loss of market share from gold because of Bitcoin. At the same time, gold may/should increase in price as fiat money continues to fall.

At the point that fiat money becomes worthless, then is a good time to revisit these calculations to find the difference where Bitcoin would become on par with gold...or, where Bitcoin would start to take the market share of gold due to fiat money becoming irrelevant and gold/btc being the new pair to be watched. It might seem unrealistic to think about this now, I believe over the next decade this will be worth revisiting though.