If the level fell 10% in 8 weeks as you suggested, and it continued to drop 10% every 8 weeks, the level after 80 weeks would be over 3ml/mg. Give it some thought, or calculation... After 8 weeks, the nic level would be 9ml...another 8 weeks, 8.1ml...another 8 weeks, 7.29ml. In losing 10% every 8 weeks, it would not go to zero in 80 weeks, rather somewhere in the realm of 3.5ml.
In the actual test data provided by
madvapes, the 1 mg drop was for a 35 mg sample, or a drop of about 2.85% in 8 weeks. At the rate indicated by Madvapes data, the nicotine level would be about 26.2 mg/ml after 80 weeks. That's an 80 week decrease of 25%...far from 100% you have suggested.
Given the vagaries of assumed methods of nicotine measurement (this is where perception rather than reason and logic comes into play) I would speculate the measurement could be off by +/- .5ml. At +/- .5ml and the degradation of nicotine continuing at these rates, the 80 week level might be in the range of 30.3 ml/mg to 22.6 mg/ml or a total decrease of 13 to 35%.
It continues to seem to me that no reasoned extrapolation of 'the vendor's data' leads to a conclusion of 'zero nicotine at 80 weeks.'