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.

It might depend on the reason why Bitcoin can die. In case when the death is due to total ban of Bitcoin as done by all governments or regimes then there is a possibility that Bitcoin death can also mean the death of altcoins. Now, if the reason can be other than that or it is within Bitcoin like losing the appeal from the market then there is a possibility that another coin can rise up to take the vacuum of leadership.
some altcoins but not all of the altcoins because some altcoins have their own platform and if bitcoin leaves they can survive due to their flexible features more way better than bitcoin the problem only is how are they gonna market their coin to the people another introduction and new risk lies ahead.