LO - I have been reading about how the next generation of SSKs are supposed to have composite material hulls - something the USN had found feasible in the 1970s-90s:
http://www.ericgreeneassociates.com/...Composites.pdf
And there have been advanced in cancelling out the magnetic signature of metal-hulleds subs:
Demagnetising Subs
So it is possible that MADs are soon to be less-useful than they have been.