As fas as I know, Bitcoin continue existence may not be known, it has been a spectacular invention as we are now using it for our daily transactions, but the continuing survival of Bitcoin, just like gold, can't be determined by anybody. Bitcoin is just 15 years, any idea or thoughts of it's survival will be difficult to know.
in addition, Bitcoin is the first digital currency and control the entire crypto markets, I don't think there may be any currency that is able to replace Bitcoin now or in near future. Btc remains the Dominant force on the crypto space, and very limited in supply.