I think this is spot on. But we'll need to wait a bit longer than this December.
In the MtGox chart the pre-bubble pad to the $15 peak is 273 days and then the part that you don't show from the $15 peak to the bubble start is another 137 (to 1.01.2013 - the price then was still about $13.5 and it was about to start bubbling up). The downslide is 133 days - so it is about three times less.
Now the downslide was 413 days (to 14.01.2015 the bitstamp lowest point) or 629 (18.08.2015 - the bitfinex lowest point).
So if we want to have the same proportions the next bubble should start either
about 1200 days after 14.01.2015 - that is May 2018
or
about 1900 days after 18.08.2015 - that is October 2020
Wow that was surprising even for me how far away it gets.
It seems like you are treating the two bubbles in 2013 as one. There were two. It bubbled from $15-ish to $200 in a matter of months. Then crashed. Then another bubble went to $1100+ and then it crashed. So we will certainly not have to wait as long as you suggest to see approximately 1,000% gains...assuming history repeats