Bitcoin is in danger because we know this coming days and last few months a lot of good coin was release to ghe market and that's one posainble become next bitcoin. But here is the only one possible become next bitcoin after 2-3 years of waiting and it is ethereum .
Can you specify which certain coins you're referring to? I don't think there's a single coin that can replace bitcoin in terms of security, functionality, and adoption. I think ETH can
(but I'm not saying it will) replace bitcoin in the #1 spot though, but not replace in terms of usability since both coins are made for different purposes.