It's really hard to decide between what make a great NX announcement for me and what would make a great NX announcement for the future of Nintendo.
One dream I've had for a while which I think would be good for me and good for Nintendo is a Virtual Console subscription service. Still have it so you can buy Virtual Console games as you can on Wii U, but also allow you to sign up for a subscription service that allows you unlimited* access to Virtual Console games while your subscription is active. I'd probably be prepared to spend double or triple the money on such a subscription than I currently do on Virtual Console games, so I feel this would be a money earner for Nintendo.
*Probably some limits would be imposed, like maybe x number of games per month, or maybe only NES and SNES and not the newer consoles (or a more expensive package that includes N64 games).