Current project tools force mouse use for basic organization, slowing down users who think best at the keyboard. The few keyboard-centric tools lack project management features.
Build an outliner with first-class keyboard support that can handle tasks, notes and basic scheduling. Include Vim-style navigation and markup shortcuts for power users.
Monetize through paid licenses. Could offer team versions with collaboration features.
Start with local single-user version, then add sync and sharing. Focus on perfecting the core keyboard experience first.
Risk is balancing simplicity with powerful features. Needs strong opinionation about what to leave out.