If an alt coin becomes valuable enough, hopefully its value won’t be directly tied to BTC...although that seems to be the case now, I don’t believe that will be in the future.

If your alt coin goes up in value you sell it and even if bitcoin is down you’re still getting the same value in USD regardless. You would just have to sell to fiat immediately if that’s what your goal was, so you don’t lose money if BTC goes down or something...