Also leaving Alts on Exchanges is the same as leaving BTC there since when you come to sell back into BTC your leaving it up to a third party to choose between BTC and BCC . . . or whichever chain . . .
Am I right?
You are right so don't just leave altcoins on btc exchanges. I'd rather sell now all of my altcoin stash rather than leaving them on exchange. My course of action tough is to sell some alts and hold some on a wallet that I have complete control with, or ones I own a private key. Even alts will be affected on august 1 if there will be a split so its better to prepare for it now, decide what to sell and what to hold.