That new high is not hard for bitcoin to reach. In 2017, bitcoin trading in 1000$ in January and reach 18000$ in December. That is x18 time, and next year this can happen again and may be stronger rise.
$50k on dec2018 might be possible to achieved. Yes its not hard for bitcoin to reach at this price because we already saw and observe bitcoin this year and it really amaze us all users. Year 2018 would be very stronger value for bitcoin so for me it is possible to achieve the price.