i don't think we can reach $20k this year but it is not at all far away as you think it is. in fact $20k is so much closer than you can even imagine. you are feeling the same as how people used to think about 8 months ago about seeing $10k which also was considered "far away".
i don't think it will be reached only because each time (in each cycle) we get closer to the ATH of previous time it becomes increasingly hard to break it. so the rise slows down the closer we get to that arbitrary number. you can look at $1200 in 2017 and see how that looked like.
Much closer is how much in the time frame, 6 months, 1 or maybe 2 year? I personally have an opinion that the next big bull run probably has the greatest chance of happening for at least 6 months to a year and a half after halving. If we look at what are predictions from some experts, most of them saying that $100k+ we can expect around the year 2022 or after that.
2017 was a specific year, and rise is starting after 6+ month after halving, with big pump in December powered by Bitcoin futures launch and probably the biggest FOMO effect created by the media. I see special show on my local TV about Bitcoin, and almost all newspapers have reported about this on the front pages.
The price won't go up on its own, a large amount of money is needed to start a new bull run, I think it's totally unrealistic to expect small investors to invest their money so easily after they get burn back in 2017/2018.