I think to have a bull market up-coming is the best way to move all the money that you have in altcoins to bitcoin, because with market dominance of Bitcoin the market will go green, and the bull run with start, as far as I am concerned from the previous experience of the bull run more than 55% bitcoin was dominant in the market.
Suggestions?
I would think that you should not move all of your altcoins to bitcoin because let's say for instance, the value of bitcoin now is around 4000$ and after the bull market it becomes 8000$ and ethereum from 150$ to 320$. Then it would be profitable if you have move your altcoins to ethereum. But either way, this Q1 of 2019 will be profitable to all people.