yes litecoin and bitcoin have the biggest networks.
not anymore! so do you think doge too big to fail now?
DOGE = 96 GH/s
LITECOIN = 79 GH/s
http://www.reddit.com/r/litecoinmining/comments/1vsd1g/dogecoin_just_overtook_litecoin_total_network/
i think from what we've seen in the last 3 days demonstrates that no scrypt coin is really immune to a possible attack, and would be vulnerable to a large influx of asic miners. This includes Litecoin, which no longer has a bigger network than dogecoin. As many others have said in other threads distributed scrypt ASICs will be essential to maintain the security of these altcoins to prevent attacks.