what are the key reasons to expect $4000 in light of the uncertainty in the coming months?
The most important reason that could prove to have an upside surge in the price of Bitcoins would be SegWit.
Activation of SegWit as well as its work are both going to appreciate the value of Bitcoins in fiat because if fees get lowered back to where they used to be and confirmation speeds boost up, then 4000 is nothing and it could even head up to 5000.