How long would it take for big banks to make cryptocurrencies mainstream? (My thoughts)

Jordan Belfort said this not so long ago:
"Sooner or later, a central bank or a consortium is going to issue their own cryptocurrency and that's what will take hold."

Of course, he changed his stance quite quickly and added this:
"I'm not saying you should or shouldn't buy bitcoin, but [what] I'm saying is I personally, myself, would be very, very careful about investing a lot of money in something that could vanish very quickly,"

Source of Belfort's quotes: https://www.coindesk.com/wolf-wall-street-jordan-belfort-jamie-dimon-right-bitcoin/

I believe there is some truth in what he said. In my opinion, banks will stand behind some. Even though I think this is a solid long-term investment, you shouldn't hold any amount of money in cryptocurrencies you are afraid to lose. But bank backed cryptos "destroying" all the rest or could all "vanish very quickly"? I doubt that. Fiat money is a whole different topic though. John McAfee predicts a $500k price for Bitcoin within 3 years. Of course, he isn't the only influential person who predicts a really bright future for cryptocurrencies. And if the price goes high enough, there will be a point when a lot more people will start to think "Why would I hold my money in $, €, £, etc?"

We are the early adopters, but soon it will be common to have some Bitcoins, Ethereum, etc. for a lot more people. Why do I think that? Well, think about how fast everything changes. I remember the time when merely having a computer or using it on a daily was "geek stuff". Or mobile phones and then smartphones. All these things are common nowadays. I'm a young guy and still experienced the whole transition! The internet was also like that and playing video games online or even against each other with 2-3 computers was special. Now there are grandparents streaming how they play games. :):) Like Shirley Curry who has ~250k subscribers. I'm not kidding:

When it comes to fiat, people at the top can invest, and make other people invest, an insane amount of money into cryptos quite fast if they want.  I won't mention a specific, existing cryptocurrency and this example isn't a real scenario. I just thought about this early in the morning. Let's say some big banks(with the aid of governments) want to implement their own cryptocurrency because it's faster and cheaper than fiat and with that new method they predict way more profit than with the traditional. What do you think how long would it take to say: "Pay your loans in "Loan Coin" and save 5%"? Most people would swap in a heartbeat. People use shopping cards at different supermarkets for as little as a 0.5% discount because why not? Why would they act differently if banks would come up with something that could save money? And with that amount of $$$ pouring in, the price of their preferred crypto would skyrocket and they would hold an amount we can't even comprehend. Will they use exactly this for the transition? Probably something way more efficient.

I don't know when will this happen or how exactly, but eventually, they will stand behind some cryptocurrencies. Why wouldn't they? WHEN they believe it's time to stop all the FUD, the narrative will change into glorification... It all depends on what's good for them at the moment. If they don't have an exact plan to come out really good out of this(I doubt that), then they will act for the sake of damage control. Just think about how fast people's thinking change before/during elections. Now imagine if they campaign for some currencies the same way.