As soon as Bitcoin reaches 20k and new ATH, new hype will start. At that time fresh money will start to pour into Bitcoin and from there into alts. Right now there is no fresh money. Or very little and Bitcoin grow from altcoins. When this will happen who knows.
The retail investors never came back into the stock market after they got fleeced in 2008. The supply of greater fools is not unlimited. The boomers are getting old and more financially conservative. The Millennials do not have any money.
This turn up for BTC appears to be institutions taking over, as they
replace the shitcoins with Facebooks Libra and then prepare to back Libra with Bitcoin after
the Core riff-raff are fleeced with the SegWit donations (c.f. also
the BCTalk thread).