There's an argument to be made that there could be a BTC supply shortage on exchanges prior to August 1st, due to a larger percentage of people pulling their bitcoins off into wallets they control. If that happens, but demand remains constant, you could see the price go higher. I'm currently bearish, but there might be an opportunity there for people willing to take the risk of keeping their bitcoins for sale on the exchanges nearer to August 1st.
Keeping your coins on an exchange may be your only chance to capitalise on multiple chains. It's quite possible one or more will be so painfully slow until a difficulty change that you won't be able to move them quickly enough. By that point it may all be over.