  As the ratification of 5G New Radio technology is being completed, enabling
network architectures are expected to undertake a matching effort. Conventional
cloud and edge computing paradigms may thus become insufficient in supporting
the increasingly stringent operating requirements of
\emph{intelligent~Internet-of-Things (IoT) devices} that can move unpredictably
and at high speeds. Complementing these, the concept of fog emerges to deploy
cooperative cloud-like functions in the immediate vicinity of various moving
devices, such as connected and autonomous vehicles, on the road and in the air.
Envisioning gradual evolution of these infrastructures toward the increasingly
denser geographical distribution of fog functionality, we in this work put
forward the vision of dense moving fog for intelligent IoT applications. To
this aim, we review the recent powerful enablers, outline the main challenges
and opportunities, and corroborate the performance benefits of collaborative
dense fog operation in a characteristic use case featuring a connected fleet of
autonomous vehicles.
