That's a great question, and I'm not a Segwit expert...

I look at LTC as a hedge. I can't imagine all three Coinbase coins will move in lockstep forever - though ETH and BTC seemed to move for the past couple months in a pretty similar pattern.

BTC activating Segwit would not necessarily be a bad thing for LTC; there's a name recognition pattern there, but I honestly think people will be looking for a coin that could become "the next BTC." Or the next ETH. And so on.

As always, your investment could go to zero - so that remains a possibility, too.