As a bitcoin test network, it's still useful
You can sell LTC for profits.
But you cannot sell any Bitcoin testnet coins for anything.
Litecoin once again proved that he is reliable coin, so many doubted but yet he is still here, was it testcoin/testnetwork or not he is here.
Current price say this way and he will remain here for long time, he wont have that second place anymore like in the start but he will remain to be good and stable altcoin as it had been so far.