There is nothing to stop people from issuing LTC (or whatever) trading derivatives, similar to how XBTC has been created on Counterparty as essentially a proxy for BTC. We encourage folks in the community to come up with and enact these kinds of use-cases (in a thoughtful, responsible manner, not unlike how XBTC was created and is operated).
XBTC is cool, but it still leaves us with Counterparty risk. If there were additional ways to help mitigate that risk, either with
XCP backed assets, or say, with OT style voting pools, I think it'd make the Counterparty ecosystem even more attractive.