Agreed most alts will not give us much prospects in the long run but to say they are all doomed is just rubbish. Theres a lot of potential  for ltc and room for at least one more in the long term altcoin ecosystem. Mainly because BTC mining is all but dead for those who have anything less than Thash power, and the BTC price will probably end up being $500 once it becomes entirely mainstream: like amazon accepting it, or airlines for in flight purchases and 'Wall st' investors start sniffing around.... and once those serious 'Wall st' investors start publicly putting some backing into the cryptocoin world, they will want to make some serious returns- too late to do that with BTC so the non-BTC coins are where they will look.

Granted, once BTC gets mainstream there will prob be a lot of serious pressure on the other alt coins to go away (like BTC scrypt, god help it). So it wont just be a case of how many miners and forum 'likes' anymore, but some proper corp-political like lobbyists will start throwing weight around. But now that China is keeping an eye on LTC, it wont go away as easily as the others and this leaves the door open for more than 'just BTC' long term scenario.

Like 'real life' minerals and metals: gold (BTC)is everyones favourite, but theres plenty to be said for silver (LTC) and even iron (insert coin of choice).