Just like no one predicted bitcoin to reach this much growth back then, I believe it is the same as now.
The Bitcoin founder, Satoshi Nakamoto made his prediction on Bitcoin future before his disappearance.
Right. Otherwise we couldn't have a finite limit of 21 million coins, because there would always need to be some minimum reward for generating. In a few decades when the reward gets too small, the transaction fee will become the main compensation for nodes. I'm sure that in 20 years there will either be very large transaction volume or no volume.
Prediction is about Bitcoin transaction volume, not directly about its price, but it's easily to connect between demand and price. Higher demand in higher transaction volume means higher price.