The problem would be the massive subjective lag for getting any debugging feedback and the overhead of remembering what you were working on a year ago.

Yes, I admit it would not be an ideal coding environment, but it could be done. Brain-time is cheap, so you have plenty of cycles to spare relearning your code from scratch after each debug cycle. You also have plenty of time to spare to write immaculate documentation, to ease the relearning process.

I suspect that making a massively parallel compiler/linker/language would be the most effective.

I agree. It would be my first project. Even if it took 100,000 years that's only a month real time! Hopefully I wouldn't go insane before finishing =D