Hmm, after this harsh correction now in December, I think there will be an upswing again for bitcoin in January. A few of the altcoins will probably have a great run in 2018. My guess for the new ATH of bitcoin in 2018 lies somewhere between 50.000 and 100.000 $
People are simply taking their profits to close the year with a positive balance. Bitcoin remains one of the best speculative assets in the world and it will not be forgotten and abandoned just like that. We are reaching a point where something has to be done with transaction costs and block sizes. It will either end up with the lightning network taking over and pumping the value of BTC once again, or an altcoin pretender becoming the new king. If that happens it will either be ETH or BCH, although I'm still a believer in BTC and will keep the majority of money in it.