I'm one of those who was pushed into a cell phone kicking and screaming and don't get me started on upgrading. Every 2 years to upgrade an entirely new phone really burns me up. I have no idea how or why people do it annually.
1.They break them.
2. They see their friends with the fancy new version (I mean who wouldn't love it if their photos were actually little videos and were unlocked with a fingerprint scan
3. They get suckered in to it with clever hidden subsidies, monthly payments making the new version "free" (I'm lookin' at you AT&T NEXT plan!).
None of the three reasons above seem like they would apply to the NX for the following reasons:
1. Nintendo products are designed to be practically unbreakable and handled by small children.
2. Nintendo has a chance of going viral again with a popular new device, but it won't feel like a fundamental part of your person like a cell phone does.
3. Nintendo would just charge you for the full price of the device up front.
I think NX will be designed to be upgradeable, but I can't see them matching the cell phone makers by coming out with a new version every year.