The current version of the 3DS will be as unplayable in 5 years as the original DS is now.
Given that I've had a fat DS and enjoyed it from when it was first released up until about a month ago, I'm going to go with 'not at all'.
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"As the size of an explosion increases, the number of social situations it is incapable of solving approaches zero." -Vaarsuvius, Order of the Stick