The site reports that Nintendo is in the process of creating a “follow-up” of sorts to the 3DS. Specifically, it seems as though Nintendo is working on a 3DS Lite. The new system would feature an enhanced battery and would be thinner than the current 3DS.
If Nintendo is going in this direction, it wouldn’t be at all surprising. Both the Game Boy Advance and the DS saw numerous iterations that improved on initial hardware.
For now, this report should be treated as a rumor. Having said that, Nikkei has known to be quite accurate in the past. Personally I don't really like to post up on rumors but a lot of sites were reporting this as well.