A exchange rate in the billions of dollars is possible if the dollar enters hyperinflation. In that case, the exchange rate of Bitcoin could reach billions of dollars. However, if inflation continues as it has so far with real inflation around 7 to 10 percent Bitcoin will likely continue to grow in line with inflation, and probably, after the halving in 2032, it will surpass 1 million dollars.
It is about million, not about billion but you are right about that in a scenario of Bitcoin price skyrockets to $1 million of dollars in a very short coming time. It will only possible to happen if the world has massive inflation in fiat currency supply and I don't want to live in such a hyperinflationary world.
Well... Either millions or billions are all speculations to be emphasized be cause we are only predicting based our emotional differences and analytical ideologies to determine what possible values Bitcoin price could acquire in the short or long term.
On the other side, we don't have to expect too far at what price Bitcoin would be in the close term time. Like it is now, Bitcoin ATH at @ $24K on a gradual trends. So the price did not jump or skyrocketed from the bottom to the peak at which gave us the believe that $150K-$500K is possible as long we can only give it time to acquire.
Speculating about billions of $ is quite positive but while we would speculate a shorter time, we should expect a range closer to the ATH. So I don't either speculate about million $ now but a closer range while I am optimistic that millions $ is possible. Maybe after achieving it we can hope further higher price.