The central enemy of reliability is complexity.
― Geer et al., 2003
The cloud might not be a sustainable model for handling computation in massive IoT scenarios. Instead lots of the data processing might need to be done close to the devices. Resources, efficiency and latency are reasons where such a system “on the edge” might be beneficial or even a hard requirement.
A very interesting topic! A great introduction is this episode of the Software Engineering Daily podcast with Peter Levine: The End of Cloud Computing with Peter Levine. Peter also has a talk about the very topic.
Enjoy the listen and make sure to check the other episodes, it is a great Podcast!