It has no valid use.
So probably not...
It's essentially Bitcoin with less security.
There are plenty of uses for a currency to compliment Bitcoin. Just having an alternative to Bitcoin is reason enough to have Litecoin. It is all new to everyone, and could have many possibilities that we haven't seen yet. I certainly wouldn't feel comfortable with any of the other alternates out there.
Absolutely. Litecoin touts itself as the silver to Bitcoin's gold, and when I mine them, it kind of feels that way. I truly hope it DOES prosper and work in tandem with the Bitcoin economy.
I don't think that is what FlipPro meant for "valid use". Just being an alternative isn't valid use. Neither how it feels. Litecoin just doesn't bring enough innovation to justify itself as something you would
need to use "in parallel". There is nothing inherently wrong with Litecoin, replace Bitcoin with Litecoin, and Bitcoin has no "valid use", since they are essentially the same thing. Doesn't matter where you can use or exchange them. If everyone accepted Litecoin AND Bitcoin, both would have the same rate of redundancy.
Take a few steps back and try to keep things in perspective. Most kinds of selective pressure Bitcoin might face in the future, Litecoin will face too. I mentioned scalability issues for a reason, since it's probably the biggest problem both would face, and what I would expect from Bitcoin's "silver" version is to solve that problem, since the silver-as-money does exactly that for gold. Litecoin
is still gold with this metric.
In summary, if we are to have a "silver" crypto-currency as an alternative to Bitcoin's "gold", it needs to have properties that are essential to the survival of crypto-currencies as a whole.
I'm thinking of mainly off-line transactions and scalability. As far as I can think of, all block-chain solutions to the problem can successfully be integrated into Bitcoin (you probably can solve off-line transactions with signed addresses and centralized guarantee, but scalability is not ultimately solved). All other solutions can be implemented as a higher-level structure on top of Bitcoin, either as digital cash or as ripple-like systems, some of which would be ultimately scalable and allow off-line transactions. These will be Bitcoin's silver.
(@the joint: I know you like philosophizing on these issues. Think of it this way. With litecoin's metric of being a "silver" of something, you could in turn create the silver of Litecoin's gold, by essentially modifying some constants. This goes ad infinitum. One legitimacy I can think of could arise from the developing standpoint. If there is some experimental feaure Bitcoin developers won't implement, and Litecoin does, and it proves to be of alternative use (arguably faster confirmation rate is something like that but not enough), then there might be a case to be made. So yes, if there is a reason we'd expect for the list of features to diverge, then Litecoin could prosper.)
With improvements in client and network security, there could be many benefits to having two Bitcoin-like currencies, especially when one network is primarily backed by GPU power and the other is backed by CPU power. Obviously, security updates to each currency would be necessary if and when quantum computing scales up from its infant stages. But, being able to shift your assets between these two currencies could become extremely practical, much like how gold and silver are stored while quarters, nickels, dimes, and pennies are used in everyday exchange. One currency could be more active, and the other more passive.
Or, one could become more regulated than the other, with each serving its own unique purposes in society. Two similar currencies could also help each other grow -- it's easier to mine litecoins at least in terms of hardware accessibility, and this could help spur the adoption of Bitcoin and Litecoin alike. Merchants familiar with one could easily become acquainted with the other, and this could open up more payment options for consumers. And in the event that one network becomes compromised for whatever reason, assets stemming from the damaged network could be converted.
I'm sure there are other potential benefits as well. But, I do agree with most of what you're saying -- any number of potential currencies could do the same as Litecoin, if not more. But hey, when you're mining them, you want it to prosper at least a little bit.