Here's my take on it. I don't believe Cryptocurrencies are just a fad. Many Coins will continue to prosper. That being said, there are too many new coins/new entrants. Just search ICOs on twitter. Seems like everyone and their brother is starting a new coin . The vast majority of these will fail and eventually the market will consolidate to only a few coins which will continue skyrocket.
One of the biggest issues right now in my opinion is manipulation. A few very wealthy investors can run the price up or down and profit off the change. Pump and dump. Buy when it crashes and so on and so forth. Traditional investment vehicles at least have regulations in place. (Sure people break these rules all the time but it's at least keeping stuff in check somewhat). Bitcoin futures is likely to exacerbate the manipulation.
Edit: Also, this recent crash (or correction) is going to hurt/delay the adoption of CryptoCurrencies. It's only in the past couple months that Crypto Currencies came onto the radar for everyday folk. A lot of people who bought in when it was around 18-19k lost a fair amount and I'm concerned this correction turned them against Crypto.
Notice I say correction. I think adoption will continue UNLESS a major western country bans it. If that happens I think alot will follow. In all honesty I think there is a reasonable chance that this could happen. A bunch of VERY wealthy individuals/industries (banking) do not want it to succeed. Sure they can profit off of crypto, but in all honesty they would lose out over the long term compared to if Crypto wasn't around. Essentially they lose their monopoly on the industry. Already seeing a bunch of bank execs bad mouthing it and calling it a bubble/will fail. Wouldn't be surprised if they are actively lobbying $ against it already.