A 720p display would be enough considering the size of the screen, going 1080p wouldn't even be really noticeable -or at all - for most people.
So my take is: stay on 720p and focus on delivering the exact same performance than the docked counterpart, just with a smaller resolution. Also, Nintendo should ensure to try and make dips below 720p a very rare occurrence, as that's much more visually disturbing than being at 720p in general for the handheld part.
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454 List as Google Doc: https://docs.google.com/spreadsheets/d/1aW2hXQT1TheElVS7z-F3pP-7nbqdrDqWNTxl6JoJWBY/edit?usp=sharing
The Steam/GOG key gifting thread: https://gamrconnect.vgchartz.com/thread/242024/the-steamgog-key-gifting-thread/1/
Free Pc Games thread: https://gamrconnect.vgchartz.com/thread/248138/free-pc-games/1/
