Im holding the alts I like.. Like steem, bitshares, PPY and etc.. Sold some of my other alts and my Eth for BTC so I can take advantage of the fork. I am guessing thats what everyone is doing. Once the fork happens and I get both my coins. I will trade them back into alts.. I expect a lot of people are going to do this, and it may be another large alt pump for a bit after. Just my guess.
So the price will end high for btc and lower for alts pre-fork, and once it opens, it will go down and all the alts will head upwards..