Do you think Bitcoin will remain the most dominant coin both short and long term? Even though it does not remain the most dominant coin, this will not be the same as saying that Bitcoin wont exist long term.
Seeing how bitcoin is gaining demand and popularity in the market, I can say that there is still no better and potential competitor in the market. People are still into bitcoin since most alternative coins are likely dependent on its price. Bitcoin is still one of the best established coin made, it has a good community that is backing up which is an assurance of its good future.