Given bitcoin's leader role in cryptocurrency, it is very hard or impossible for bitcoin to disappear or replaced by another cryptocurrency completely as bitcoin has big user base and miners. However, it is possible that some alt coins with more advanced feature may overtake bitcoin in term of market cap.
Bitcoin is becoming stronger from time to time and that is the reason that we cannot even think that bitcoin will ever replace by another crypto currency, i think that with the passage of time bitcoin will become more stronger because of the increasing number of bitcoin users and their interest. Even in backward countries now bitcoin is becoming popular from time to time.