There are some standards which aims to predict the life cycle of each kind of electronic devices subjected to many environmental conditions. One of the most consistent in my oppinion is the MIL-HDBK-217F, which gives parametrically the value in years in function of the temperature inserted on the formulas.
A practical procedure that could be used to estimate the expected life of a complete product in a systematic way would be putting these values in a proper field on the library schematic of the components placed at a design, so that once the BOM list is generated, a simple application that reads text of this file is able to assign to each component the value calculated for certain temperature, therefore by employng some statistical analysis, could get the life cycle of the whole product.
For the specific case above, you can try to identify on this board the most critical item which accounts the lowest MTBF at current temperature , and then calculate at the best case, what would be the time decreasing due solely to this component.