LTC is essentially a BTC fork with faster confirmations resulting in a less secure network. However, bitcoin payment processing companies can use off the block transactions for instant confirmations. I'm not saying LTC is useless. It just doesn't do anything bitcoin doesn't accept for send money slightly faster at the expense of security. But as the masses adopt, they will almost certainly be using simplified services that allow for off the block transactions.
I don't wish LTC would go away, I think it is and always will be a secondary to BTC. If anything, something like peercoin should prove to be more competition, as it is actually based on proof of stake AND proof of work, instead of just copying bitcoin and making a slight modification.
In the future an alt currency with real benefits over BTC could certainly be developed. Just hasn't happened yet.
The main benefit over BTC would be the Scrypt hashing algorithm, for which mass production of ASIC's is less feasible, at least not by a factor of 1000 over GPU's like we're seeing on Bitcoin at the moment.
This means litecoin stays out of the hands of chinese chip monopolists, and into the hands of the well distributed userbase of graphics cards.