As long as your coins are in your own wallet (not an exchange) and you don't touch them nothing bad can happen.

Ultimately, if both chains continue to exist (a big if), you will have the same amount of both new types of coin. When it comes to spending either of those coins you'll have to think about it, see which chain your wallet software works with.

If anyone tells you one coin will be worth more than other, they are guessing. We don't know for sure what will happen. The risk-averse thing to do is to hold fast and see what happens.

Maybe gamblers will sell one of their coins to gain more of the other, but they can easily get burned if things don't turn out how they expect.