Features are added or dropped depending on the commercial market needs. Commercial product stability is tied to end equipment life cycles. These life cycles are continually decreasing. For example, in the case of computers the life cycle of parts is approaching six months. Part capability, both electrical and environmental, is balanced against the market requirements.
Capability is tied directly to part cost.
The possibility of obsolescence also increases as the market moves to different packages higher speed and new devices. To obtain extended temperature electrical performance many issues must be addressed. For a part to perform over extended temperature it may be necessary to adjust the wafer fabrication process. In more severe cases it may be necessary to totally redesign the part. If this is not possible, i.e., affects commercial performance negatively, the manufacturer may continue to produce the older die revision for the military customer.