What adoption ?
Adoption that happened from 2014 to 2018.
About the length of the bear market is hard to say. Last one was a year and a half. But reason for that was that we had 2 bull runs in 2013. So this bear market should be shorter. But because of more adoption and less volatility should also be longer then previous. So this are + and - what means that might be similar as was last.
Yes that surely will be a shorter one, because bitcoin is now getting great support from the investors and they will never want bitcoin value to drop so much, in fact they know the importance of bitcoin and will never sell their holding bitcoin but will try to manage to hold their bitcoin for a good time when its price will start increasing again. I think bitcoin still has good potential and 2018 will be another great year for bitcoin price.
There us of course bigger support, but they also need to support way higher price. in 2014 was supported few $100 price and now will be supported few $1000 price. For tat you need 10 times more supporters as in 2014.