I think btc will reach about $500 sustained price by 2020.
I think you're wrong by several orders of magnitude in one direction or the other. i.e. $50,000 or $5.
I agree with the latter post, although not necessarily 50K, could be 10K-50K or $5
Reason#1: $500 is way too little for serious transactions as market cap of ALL bitcoins would be less than 10bil (19.5-19.6 mil BTC in 2020 X $500).
Serious currencies are trading in trillions (total ~$5 trillion a day)
At 50K bitcoin will be ~950 bil, still not enough to support major currencies trading, but getting there.
Reason#2: i don't think that serious exchanges can survive on a single measly 10b asset price item. We have multiple exchanges being worked on.
If it fails, then $5 is much more likely than $500