It's quite simple. Bitcoin is / was a big mainstream pump and dump. The only reason it's hung around so long is because of HODLR's and newbies. The real pros, the sharks, pumped this thing like a dirty pig and dumped it long ago. Anything they're doing now is just second and third helpings. Bitcoin will be around awhile, no doubt, but as the years pass and newbies lose money on it, it's relevancy will disolve. Just my opinion I may be wrong, and I have domains in all forms of it so it affects me as well. Bitcoins value is simply a current day trend. The value is a combo of psychology, 2018 trends, and unfortunately alot of new users making mistakes getting in too late. I feel if it keeps going down and possibly hits like $3500-3800 we may be in for a huge decline or even possibly a permanant huge decline. It won't ever recover to huge metrics again like the 8k and 18k moments because those moments were purely psychological and trending and it would take a huge news report something incredibly positive for it to happen again and absolutely game changing imo.
Will trends go to a new coin? Most likely. In my opinion, one of the current trending low coins will step up and take Bitcoins place. It might be in a year, maybe two with some new "trending mainstream promise".