4 to 8 years is a very long time and one will barely be able to hold for that long, considering there will be a lot of bear and bull cycles in between these years, it will be much more profitable if someone buys and sells at the perfect intervals between these bear and bull cycles instead of just holding whether the market is up and down. If I have bought Bitcoins when it was at around $16k or $17k and then it goes above $60k, I would probably sell as soon as I see the market coming down and wait for the next cycle.
That way, I will earn profits from the dips and will also profit if the market goes very high, by the time 8 years have passed, I will have earned way more than what I could earn if I only held for all these years. That is what I would do, I'm not sure about others though.
I think finding those perfect intervals is the issue and many people fail to do that. I think that's the main reason why we are not seeing that happening all that frequently. I think the best thing to do in this case to make sure that it doesn't really get away from us too quickly.
I think long term holding is profitable in the sense that it could help us get better at results instead of trying to make is be a trader. I hope those people who plan up to become traders could buy at the bottom and sell later on, that's definitely a good thing. But that doesn't change the fact that it is not going to happen that easily. All in all I think it is going to be a big deal, and hope that it will be as easy as it gets for a long time. If we can arrange that, then we are going to be fine.