Bitcoin is a very popular crypto coin today, we know that Bitcoin will be very expensive in the future but I imagine if Bitcoin die, whether there will be hope for the future of altcoin? because most altcoin exchanges are to bitcoins
your opinion is highly appreciated.

In my own opinion, if bitcoin dies altcoin will die too because both of them has a connection to each other. But it still depends in a situation like what if bitcoin dumps in the market and altcoin pumps up, altcoin surely would not die because bitcoin do not have anymore value if that happens.
Until the bubble of the cryptocurrency world be end, you will not see Bitcoin or Altcoin die, I do not think only Bitcoin dies or Altcoin dies can make others cryptocurrencies die too. Because the whale are the mover of the market and they will choose one of both or both to control the trending.