What I would love to see in the next release of Raspberry Pi is an onboard ADC for user accessible analog i/o on the GPIO, removing the need for an add on board. This would make it far easier for beginners to make projects that interface to the world around them, whilst still being able to use a desktop computing environment.
In combination with the analog i/o it would be fantastic if the new Maynard / Wayland desktop included desktop widgets that interface to the Raspberry Pi GPIO and a generic USB HID inherently.
That way people could drag and drop control and instrumentation directly on to their desktops.
A speedometer dial that took input from a user selectable analog port.
A desktop rocker switch widget that controlled the output on a bit on the digital i/o
A bar graph that took input from either multiple digital i/o or an analog port.
A potentiometer that can control the output to an analog port.
I think there is potential for some really interesting projects to come out of this.