One is BITCOIN
One is Bitcoin Cash (a new altcoin, not the REAL BTC)
The Forks that Survives is the Real Bitcoin , and the survivor will be Bitcoin Cash.
Plus on segwitcoin , if everything goes to G.Maxwell's plan, you will only use LN ,
You won't be able to afford Onchain transactions, Offchain transactions are not bitcoin , only Onchain.
╥Aztek
To simplify things, they are all going to exist, however, there might be major n minor chain of bitcoin. With miners hopping between chain, its fluctuations like crazy. There is no unity.
I really think it will start a new wave of coins that are built to challenge the chain leaders. Look for a Scrypt coin to overtake LTC, or an X11 to take over Dash. We already see a lot of chain jumping among miners on those algos, and once they get smart and implement an EDA similar to BCH they will grow.