The surprise for scrypt miners will come when mining scrypt is not profitable either. Who would trade ASIC earned BTC for GPU earned LTC at an effective loss? Yes I do believe the LTC economy is just an accessory to the BTC economy and can't stand up on its own right.
I agree, and then difficulty will drop until enough people are making a profit, somewhere someone will be mining scrypt profitable but unless you have cheap power and are prepared to optimize your rigs for efficiency I wouldn't bother. Worst case scenario scrypt mining in 6 months consists of people with free power looking for pennies on the bottom of a very deep well, but I doubt it will get that bad.
The thing LTC has going for it is when/if mtgox finally implements trading and fuel another bubble for a few weeks/months, long term I don't see even that saving profitable scrypt mining for most people however.
I agree - moreover, scrypt coins are doomed to failure by their very design. You cannot design a digital process that someone isn't going to be able to build hardware... to perform faster for less power. So if litecoin (for example) ever saw some decent numbers in it's price (say between 7 and 15 bucks a coin) almost immediately someone would come out with an FPGA to mine it and the entire thing would go tits up.