At some point you have to attaching a moving part (the wheel) to a stationary part (the fork) and that means you'll need a bearing (not necessarily a ball bearing). A hub is basically just a shell to which spokes can be connected, and a bearing to allow attachment.

There are hubless bicycle wheels, but they're horses of a different color.

Actually most of these are spokeless but not hubless. The hub is simply enlarged out to a hoop (the inner race of the bearing), and the rim and tire run around it (the outer race of the bearing).

Other designs are hubless, where the fork is supported on rotating rim and tire by 3 or more rollers. It's similar to a monorail concept bent into a hoop.

Sadly while cool looking none of these match the traditional spoked wheel on a bearing design in efficiency.