if this, if that, if...., if....
here is another if:
if POS will happen, i think ETH will come down first because ETH miners will switch to ETC....

Proof of stake (POS) will not take ethereum price down because POS is an innovation coming into Ethereum project/blockchain as the case may be.
i think it won't go up that high - maybe 2k for 2018
You think $2k for ethereum in 2018 but I believe ethereum will definitely surpass that that of your thinking guy