What do you think about this?
I don't think parity is possible, meaning that, it's just impossible that both coins have the same price.
So judging from this premise, one of the two coins, will go down, or one of the two coins, will go up while the other one stays where it is at best, or goes down too.
If I had to bet, it's pretty obvious BTC is the winning coin. It has the Core devs on board, it's the legacy chain, and it has segwit which is good, unless you subscribe to the anti-segwit conspiracy theories.
Bitcoin's existence is far from disappearing but like any other investments, the risk of losing your money is normal. Bitcoin has shown its potential over the years by the constant increase on its price but there are also external factors that significantly decrease its price like China's banning of ICO in their country etc. One cannot simply protect and secure bitcoin due to its decentralized nature, the primary factor on why bitcoin is still alive is due to the sheer volume of investors and individuals who utilize it onto transactions. Even some retailers are starting to accept bitcoin as a payment for their products.