"Realistic prediction", most of the time the btc price predictions are based on assumptions, speculations, and knowledge about market movements, but 90% of the time (and I'm being nice here) those predictions end up being innacurate. Just look at Tom Lee, a btc permabull from wall street who always tries to predict the btc price and never gets it right...Or look at those who remained bearish and predicted sub 2k months ago...IMO there's no such thing as a realistic prediction in the crypto market.
But to be sustainable it would have to be supported by something, maybe if a country or two adopted it as their national currency.
Very, very unlikely.