Yes. I'm 100% sure BTC can pass again 20$k. But I think it will happen in 2020 or 2021. 2018 is the very very bad year to the crypto. The whole market is like a bearish market. However at this time it difficult to pass 20$k. But we can see some pump this year, but it not a strong pump. Finally, My opinion is, Bitcoin will rise up again and pass 20$k. So be patient and wait for the pass 20$k.
I think already in early 2019 bitcoin can overcome 20k. the market has long been falling, if there are positive news - there will be a big growth of the whole market
Bitcoin, of course, will grow up to 20,000 dollars, and up to 50,000 dollars, and will grow even higher. But there is also a small probability, and the fall of bitcoin.