3 years. :)

If history repeats Bitcoin will bubble a year after the next halfening event.

The block reward is reduced from 12.5 to 6.25 in approx 443 days.
http://www.thehalvening.com/

There is going to be a lot of hype for this deflationary moment.

Steem will surf the wave of Granddaddy Bitcoin and probably ascend the market cap rankings at the same time. Of course an epic year long crash will follow, assuming the cycle repeats.