I recently just brought both and have been playing with them, as well as reading on the forums. There are some things that raspberry pi is better at, such as video media or computer vision. You will never get to run Quake on Arduino.
However, there is stuff that arduino is better at. Most people have difficult time driving servos with the GPIO pins on the Raspberry Pi. In addition, with the default image of Ubuntu, which is not an actual real-time OS, will cause timing problems in the PWM (pulse width modulation) signals controlling the servos, resulting in jittery servos when an interrupt happens. Currently, the arduinos are better at that, plus they've been around longer, with a larger community, and accessories. Anyway, that's where it's at now.
As for the future trajectory, I can only really guess, but from where I'm standing as a beginner choosing between platforms, while they seem to be targeting education, they're targeting different use cases.
> with the default image of Ubuntu, which is not an actual real-time OS, will cause timing problems in the PWM (pulse width modulation) signals controlling the servos,
CLI / STI (or whatever the CPU specific set is), run as root.
That should solve any timing problems you've got. I've used this to successfully drive a full sized portal mill / plasma cutter from an all-in-one VIA based board.
When you're driving motors you want 100% control. Interrupts you can comfortably do without until you're in a quiet spot, then you check for them and continue.
Probably shouldn't say never. Someone has already managed to get Linux running on the 8-bit micro. Though getting it to run with acceptable performance is a another matter.
Not to quibble with the overall point, but the "default image" is Debian-based, but not derived from Ubuntu, I don't believe. Maybe they thought Raspian sounded better than Rasbuntu...
However, there is stuff that arduino is better at. Most people have difficult time driving servos with the GPIO pins on the Raspberry Pi. In addition, with the default image of Ubuntu, which is not an actual real-time OS, will cause timing problems in the PWM (pulse width modulation) signals controlling the servos, resulting in jittery servos when an interrupt happens. Currently, the arduinos are better at that, plus they've been around longer, with a larger community, and accessories. Anyway, that's where it's at now.
As for the future trajectory, I can only really guess, but from where I'm standing as a beginner choosing between platforms, while they seem to be targeting education, they're targeting different use cases.