Either Bitcoin will be a zero in the future, or be worth a lot valued in fiat currency. Personally, I find $15k calls for 2020 on the low side but there is always the chance of further crypto winters ahead. But the tech itself won't go away. In that sense, the Bitcoin price is meaningless in the long run.
How exactly is $15,000 to happen by 2020 on the lower side? Are you just saying that because the price has gone up a lot this year alone? I honestly find $15,000 by 2020 to be a very fair price -- it means that from current levels and time we'll increase with well over $3000 per year. We can't just expect from this market to increase in value with a few hundred percent each and every year. At some point we'll be facing times where not much is happening, and thus the speculative aspect will slow down significantly. With not much to look forward to, people will wait till something happens, and when nothing happens, they dump out of boredom.
