From where does BNB derive it purpose? From the exchange right. Is the exchange growing or declining? The answer is, it's growing. So personally I don't see BNB losing its value or usefulness anytime soon so far the exchange is still working and the team is still upgrading for better services.  BNB isn't like some other exchange tokens out there, this year alone the CEO has added more services etc. Although we humans can't say what will happen in the next 5 years but there are things with solid proof we can see and give credence where it is needed. Thus, so far the team is still ready to work, BNB will hardly lose its value, rather it will increase..