I feel like it is also about improvements on it as well. Imagine banking system being something similar to what it was back in the day, in this world, do you think people would use it? Like you write a paper to a bank, deposit your money, get a signature, then you take that money, go to a shop, you give that money, the shop owner calls up the bank, gets approval, writes something, you both sign it, then the shop owner goes to bank, shows the paper, and gets their money if they want to.
All these takes a huge time, and right now we just use a credit card or wire transfer and we are done, takes less than a minute. This is why I honestly believe that the innovations on blockchain that will improve bitcoin could make it spread even further, just like how it happened to banks.
I agree that there will be plenty of improvements on blockchain and bitcoin world. I think as long as we can make it both something very secure just like right now, but also something that is instant or at least near instant, like less than a minute as you said, and something that takes like just 10-20 cents per transaction, then there is no way that it can't be bigger than 500k and go above gold marketcap.
Even at this point the way it is right now, it could pass it eventually, but if that happens then things will change. ETF world will change it as well, because it's going to bring tens of billions of dollars into bitcoin market as well. So combine these two and the future looks quite bright for bitcoin without a doubt.