I believe $500,000 / BTC in 3 years was John McAfee's Original speculation, but he has since updated it to $1,000,000 / BTC in 3 years which I believe to be entirely possible.

The entire crypto market is deep in the trough right now but by the end of 2018 it will have vastly increased since the start of this year, and will continue to do so for the next few coming years in my opinion. I believe strongly in the future of crypto, so I may be biased but I definitely see Bitcoin in the $500,000 to $1,000,000 range in 3 years time.