Ok I'm sorry if I come off a little harsh but a whole lot of people here are completely ignorant of what HD means in the context Nintendo is using it here. You could take a N64 game and run it in "HD" but this is not what Nintendo is talking about. Compare a N64 game running on an emulator at 1080p to Gears of War at 1080p.
The Gears of War type HD is what Nintendo is talking about, and that has little to do with outputting the gameplay to 1080p. Anyone can do that, that's not the issue.
The issue is the fact that in order to get that kind of visual quality, they have to change their workflows completely just so they can make the kinds of games that everyone else have been doing for a while. They kind of need to do this too in order to win back the core gamers, the WiiU isn't selling well and old standard definition games aren't really going to cut it anymore.
But they have absolutely no experience with this new way of doing things because it's a completely different workflow from what they're used to, hence why they're having trouble.
To give a quick example of the type of work they now have to do (and why they're so unprepared)...the Marcus Fenix 3d model in Gears of War is about 15,000 polygons while Link in Twilight Princess was about 6900. So the Fenix model is more detailed right off the bat, but that's not the issue.
To make the Link 3d model, they probably made the 3d model by hand, then they painted a texture for it in photoshop or whatever, and more or less voila. And that's about how they've done their games since the N64 days.
Marcus Fenix on the other hand? The detail was obtained by a 3d sculpture of the character of between oh say 10-40 million polygons, which some artist had to sculpt by hand. The idea is that you sculpt a master object and then lower the detail until it works in-game. This way you don't have to do the same work multiple times if you want to use it for film or cutscenes or close-ups or whatever.
The detail then gets transferred into a special texture that gets applied the original 15,000 polygon model, making it look like the 10-40 million poly model. And if you don't have them already, you need to write shaders to interpret that special detail texture (called a normal map) to make the detail appear in-game.
Alright, now do that process for every object you can ever see in the game. Characters, environments, weapons, plants, enemies, everything. From scratch. Yeah. And that's why Nintendo's having trouble. It's a lot of work even when you're completely familiar with the workflow and Nintendo...has never done this before.
And note: this is the industry standard way of doing things in pretty much any major modern Xbox 360/PS3 title you can think of, from Skyrim, to Call of Duty, to Bioshock, to Mass Effect, to Dead Space, to Mirror's Edge. Nintendo is trying to catch up with that.
