Hans,
The maximum long-term shift of OPA2192 Vos and drift equals to the maximum input voltage offset and drift specified in the data sheet (see below). What this means is that after 10 years of constant operation at 25C, the Vos and drift may double BUT since max/min values represent 4 or 5 sigma event, the probability of the magnitude actually doubling is very remote: 1 in 225M would be outside such limit (two 4-sigma events). Since the long term shift is NOT correlated with its initial value, the more meaningful approach is to add the initial magnitude and the shift as a vector quantities, resulting in maximum offset of (+/-25uV*√2 = +/-35uV and maximum drift of +/-1uV/C*√2 = +/-1.4uV/C after 10 year operation at 25 deg C - thus, these numbers also represent probability of 4-5 sigma event (1 in 15,000 units or 1 in 1.7M units would be ouside such limit, respectively).
For more info on this topic, please see the attached Long-term Stability presentation.
