There are so many coins five years ago and until now but still Bitcoin loard it over all these coins, I don't think those altcoins are a thread although few altcoins are doing great contributing to the community, but investors prefer to be in a safe side and invest to a true decentralized coin.
Bitcoin exists for many years now and not even any altcoin become a threat to bitcoin existence. Some altcoins at first were good but eventually some of it has become zero value. So, until these days bitcoin is on top of all crypto and no other coins serves a threat.