It has the momentum and the majority mining (hash) power behind it, which is the most important thing in a cryptocurrency using proof of work. That said, nothing in this life is actually certain, and major flaws in Segwit could be found that cause the power to flip over to BCC and BTC could end up going down the drain. Or both BTC and BCC could lose out to Etherium or the USD or gold. Nobody knows the future, but the easy money is on BTC remaining the lead horse in this race.

Nobody thought MySpace or GeoCities were going anywhere either...