Bitcoin is going 9yrs old, so far no alts surpasses Bitcoin. For 9yrs it remains the king. While Bitcoin is going down, no alts remains strong. All alts are crashing too. This is the best indication that Bitcoin has no replacement.
The age of bitcoin is just a sign that it is deeply rooted in everyones heart. It will not be disappeared if everyone is still supporting it. Though there are lots of potential altcoins but it is still not as strong as the king of crypto currency.