Are digital twins useful in testing for software updates?
Absolutely. A challenge in a real-life system that software updates are coming frequently and ubiquitous and need downtime of the system which should be short as possible. After each software update, the related components must be thoroughly tested if the software update does not change the expected behavior. This testing probably expands the downtime of the system, reducing the overall performance. In the worst case a software update does not work and a downgrade to the previous version is required.
Having a digital twin of your complete system with running all components in a simulated way provides the ability that such software updates are tested in the digital twin before they are accepted to upload into the real-life system. Then tests and unexpected delays in this system can be significantly shortened, keep the performance high as expected.