I think 2018 will not be the year of bitcoin. there will be a boom from altcoin. bitcoin has too many drawbacks. And almost all altcoins have good ability, superior to bitcoin
i have read about some analysis saying this too, also some very pessimistic analysis that say btc price might crash to 3000$ again in this year and stops other coins price increase
still waiting to see what will happen, but according to them, if BTC price does breaks 12500$ this week, it will crash heavily again