Some people that try to do a fork are probably legitimately trying to come up with a better version of Bitcoin. Others like this Segwit fork are just trying to take control and piggyback on the success of Bitcoin.
I think that based on the 9 years of Bitcoins history of surviving when most people criticized and dismissed it, BTC will remain as the real Bitcoin. These forks are going to produce altcoins, but it will be hard to supplant Bitcoin as the leader. The best chance of a coin having a greater market cap is just a new altcoin that builds up a track record like Etherium.