I'll give it a shot:
Most people post conservative numbers of 1200-1500...meh.
I'll try to tackle this here.
In 2013 we started at $13 with maximum at $1165 (Bitstamp, and I will ignore the $1242 on MtGox because it was illiquid)
1165/13=89.615X
We started 2017 at $968.32 (index price), therefore I suggest that 89.615X968.32=$86775 is our upper bound (admittedly, a very unlikely one). What is a more realistic, yet probably maximum price?
I suggest to look at jl2012 exponential graph (BETI) thread.
https://bitcointalksearch.org/topic/beti-bitcoin-exponential-trend-index-and-technical-analysis-470453To break local maximum value with respect to the exponential graph few days ago was $19510 and this will be rising as we progress in a 2017, but not sure what would be the number by the end of the year. I would guesstimate, at least $25000-26000 (by Dec 31, 2017)
Therefore, if bitcoin matches what it did before either by performing super-exponentially sometime this year or matching yearly maximum appreciation, the upper boundary would be 25-87K/bitcoin.
That said, I believe that several parameters have to be activated almost simultaneously:
1. ETF has to be approved. 30% chance, in my opinion.
2. Significant indication of a currency crisis somewhere. Probability unknown, maybe 10%. So 1+2 together =3% chance
3. Some central bank decides to accumulate bitcoin and news of this leaks. Maybe 2% probability, difficult to estimate. This parameter alone would be sufficient.
So, there is a nonzero (single digits) chance of 25-87K/bitcoin in 12-18 mo.
It would be interesting to watch.