Will we see the same scenario in 2018 or it will be different this time?
No one can say for sure, I'm pretty sure it is.
The price of bitcoin can never be predicted with certainty and neither will its future. The price down after ATH has happened many time before and I don't think we are losing hope of seeing it go down again in the future. At the moment we may not see the price down to $20K immediately, but it is still possible in the future. Actually I didn't expect it to happen, but anyway nothing can prevent it from going up and down because it's a free market.
You contradict yourself you say that no one can be sure and then say you are pretty sure it is so which is it? The price of Bitcoin is a prediction game that no one wins at but there is a way to judge it and that is by looking at the historical prices after a ATH has been reached which has shown every time that a correction happens after.