I really hate to enter the arena of petty bickering but have to toss my 0.02 in anyway. . .

I had a Nokian 106 that the studs were no longer making good contact with the road after several winters (and several thousand miles) use. I first attributed this to stud wear but closer inspection showed that rather than wearing, the studs "receded" into the rubber. A colleague was suffering flats with his 106 and found the studs had "receded" enough they were puncturing the tube. While two people's experience is not definitive evidence, it does seem to point to the casing outlasting the studs.