If bitcoin does reject it. I haven't seen any big news telling that. Only themerkle.com made an article and there it's written that Segwit is expected to be 80% activated with bitcoin by this September and that miners don't support it not because of some technical reasons but because of roadmap of bitcoin core. Thus I guess btc still has chances to survive. Nevertheless, litecoin has very good chances to grow more and more in price anyway.