OK so here's my big BITCOIN prediction, for the record.
Looking at the monthly chart on log scale, I think the similarity of the retracement from Nov 13 and Dec 17 highs is really markedly similar. In both cases the price retraces to an amount closely approaching the 88.6% fib level. Notably also from a time sequence perspective the cycles have tightened slightly and we could expect the next time for the cycle to be shorter again by the same ratios. The rest is written on the chart!
Lets see how it looks in a couple of years.