In technical terms, what would happen if someone with a bunch of ASIC miners pushed their machines onto a Scrypt chain?
Obviously, an ASIC for SHA256 mining cannot do Scrypt mining.
So you are asking what would happen if an ASIC that does Scrypt were invented?
It probably depends on how the ASICs are put into play. If they are intended to be units for sale to the public, then it might be something that would benefit the leading Scrypt-based alt. If the units are intended to be used in a 51% attack, then it is lights out for whatever Scyrpt-based alt(S) they target.
I agree, if they keep the fact that they have a ASIC that does Scrypt secret, use enough to corner the market and perhaps a 51% attach, it will be lights out for that coin. Maybe the Point of Stake Scrypt Coins will be more resistant to the attack and survive. Who knows, but I am concerned about the future of Sha-256 and ASICs now. I'm glad that as far as we know Scrypt is safe.