When Ethereum finally becomes the biggest blockchain by market cap 0xBTC will become the BTC emulation that is used as a deflationary store of value on that blockchain.
Bitcoin will die and cease to be a blockchain of any importance and people will switch to investing in 0xBTC which is compatible with the Ethereum network.
Don't know where you got your prediction from but you should first know that Bitcoin and Ehereum are not the same and they solve different things so saying that Bitcoin is going to die is very interesting..