Damn, now I need to move faster. My app must be ready by the time they close Wunderlist. I expected an eventual closure, but not that soon. I've spent the last two years developing a todo app that would be a good replacement for Wunderlist (and Astrid, if anyone still remembers that). The app will include with some major / critical features both those apps lacked: proper hierarchies / first-class subtasks, automatica…
Wow. It's nice to see extensive planning like that. I usually just throw anything that seems like an important idea into a text file on the assumption that it'll be fully hashed out during production at a later time. That method entails far less work, with the caveat of occasionally wondering if you're delusional from time to time.
In any case, good luck. I hope you kick ass. If Microsoft employs their usual design aesthetic, doing so should be very possible.