Everything is ASICable...
It just requires enough incentive to be profitable
DeathAndTaxes is correct, 128k per thread is not very much as such.
And to answer my follow-up question myself, increasing scrypt security would of course make it more difficult for everyone (i e current mining gear, not only ASICs), so not a good idea if the point is to prolong GPU mining as a feasible alternative.
But returning to the initial claim of this thread (as I interpreted it) - I still wouldn't say that ASICs for BTC and ASICs for scrypt based coins means the same thing. I may need to do the math, but shooting from the hip I don't think that a "scrypt ASIC" could turn things over the way BTC ASICs do, the reason for that view still being the memory intensive processes as per the scrypt design (be it with a downsized version of the security settings).
So it is exactly the improved profitability of a scrypt coin ASIC that I doubt...