The Japanese Nikkei newspaper is reporting that, later this year, Nintendo will introduce a new version of the DSi that replaces the system's 3.25" screens with luxurious 4" screens. The new system will replace the current DSi and will retain the ¥18,900 ($205.50) price tag. According to GameLife's summary of the article, the screen size has been increased with older gamers in mind. The Nikkei article states that it'll be out in Japan sometime this year, but that plans for other countries have yet to be made.
We're inclined to believe Nikkei when it makes predictions like these. It's previously made shocking claims like the announcement of a DS system with a camera and music playback functions, and a Nintendo/Dentsu video service.