As I see, I find the only best way to predict the bearish position of Bitcoin is to keep your eye on Bitcoin dominance, When the dominance will reach 32-34% or below 50%, Bitcoin bull run will be ended. It is the only thing which happened during the 1st day whether it is 2013 or 2017.
I can only find BTC dominance data going back to April 2014. Where was it in December 2013?
I'm not sure why you're trying to predict when an altcoin season is coming when your basis is effectively that very idea: a low Bitcoin dominance means a high market cap for altcoins.
It goes with my theory that in the late stages of a bubble, money will flow into the riskiest and most speculative assets. That's retail investors, late to the party, looking for those "Bitcoin-like" gains because they feel they missed the boat.
On fundamentals alone I think there's
probably something to it, but even so, trying to predict the exact level where dominance will bottom out is futile. There have been too few of these cycles to assume everything will play out like last time.