Scenario 3: bitcoin splits into BTC (segwit deciphels) and BTU ("unlimited").
In 2017-18 price $600 on BTC chain, $300 on BTU chain; could be even lower.
By 2019 one of chains will wither more, another will gain more than proportionally, so it could be $900 BTC, $100 BTU or vice versa.
By 2020 maybe some appreciation or getting back to $1300 in a sum of chains.