4 years is not that long, and this is the usual scenario every time we hit the bear market.
This can be the safest speculation because it’s hard to know if the economy of many countries will start to recover in the next three years, we are still experiencing the problem from pandemic especially on printing too much money and with the limited supply. Bitcoin can reach new peak though in less that 4 years, once there’s a big news in the market probably it can be hit easily but if we didn’t saw improvements, then we might wait longer for that new peak.
Reaching 68k with 4 year difference is definitely a safe bet, it's not going to be that late and it's not going to be that low if you ask me, but if that's your goal than anything quicker or higher would help you out a lot. I personally believe that the best thing to do would be making sure that you are on the right path, and that will only happen if you have the long term mindset and this allows people to be on the long term mindset.
I personally believe we will reach 68k levels again by 2023 sometime, and be over 68k+ in 2024 as well, that's what I believe it will happen, that looks a lot quicker and higher but it is once again a reason to keep buying and holding bitcoin for sure.