It's all based on the size of the Revolution userbase after the first year or so. If Nintendo doesn't want a repeat of the last two gens they have to be incredibly competent. They have an uphill battle so stupid little mistakes like tiny memory cards and wacky controller designs are going to make or break them. They pretty much have to do everything perfect. That's really the only way they'll get the general public to care and they need the general public to care in order to get third parties to care.
Aside from not f*cking up they also have to do some things exceptionally. The launch lineup for example NEEDS to have an amazing killer app. Luigi's Mansion, Super Mario Advance, or Super Mario 64 DS are not going to cut it. They need something on par with Super Mario 64. First impressions are everything and if the launch lineup is lame people aren't going to give them a chance. They also have to line up some really major third party exclusives, like the Resident Evil deal except more than that. If they have to throw some cash around so be it. The extra cash spent on getting a major third party exclusive for the first year of the Rev's life will more than pay off later in system sales and third party licencing fees.
They also have to suck up to third parties. No more having the most expensive licencing fees. No more elitist attitude. They have to suck up big time. They have to give third parties an incentive to make Rev games. Cutting fees for exclusive titles, getting third party input regarding the hardware's design, publishing and localizing games for small developers are the sorts of things they have to do. If they have some truly new innovative idea that would provide a decent incentive as well providing this idea doesn't wang traditional game design.
And of course they need good marketing which is a big question mark. Making the best system ever isn't always enough. Aggressive marketing will be a key role in how many consoles are sold within that first year. MS nailed it with the JSRF bundle pack. Those are the sort of ideas Nintendo has to have. They can't assume people will just buy their stuff just because.
However the one big variable that may very well f*ck everything up is online support. If the Rev doesn't have it that will limit third party support. If a third party can't make an online game on the Rev then that's a lost game that didn't NEED to be lost. The Cube has lost titles like Burnout 3 and Godzilla 2 because it's not online. No online is a limitation and developers don't like limitations particularly when the competition is allowing that freedom. It's also a limitation that's going to become more significant next gen. Plus the lack of the feature affects systems sales. If you're missing a feature the competition has it's going to cost you sales. The Rev absolutely HAS to be online if there is to be decent third party support and Nintendo has to have plans from the get-go. If they pussyfoot around it like they did last time people are just going to assume they have no plans because that's how it turned out last time.
So it's going to be pretty hard. There's very little room for error. I think they are capable of this. Whether or not they actually pull it off is something else.