A 757 patrol aircraft could lead to an AEW family

Could a 757 maritime-patrol winner also become the basis for an AEW aircraft?

Yes; the common airframe could support an airborne-warning derivative, possibly earlier than otherwise expected.

A large production and support base encourages development of several mission variants from one airframe. A 757 maritime-patrol program would already fund sensors, power, and structural changes for naval service. Those investments could lower the risk of an airborne-early-warning derivative. Sharing the airframe might also bring the AEW version into service sooner than a separate design.