According to American Technology Research analyst P.J. McNealy and CNNMoney.com, Nintendo may introduce the follow-up to its Game Boy Advance SP portable later this year.
"We believe it is likely that the next version of the Game Boy Advance SP will ship as early as this holiday, ahead of most expectations of calendar year 2006," wrote P.J. McNealy of American Technology Research.
He speculates the new system will launch at $99, with prices of the Game Boy Advance SP falling to $49 and the Nintendo DS remaining unchanged. Official confirmation of the new Game Boy is rumored to come March 10 at the Game Developer's Conference in San Francisco, when Nintendo president Satoru Iwata gives a keynote speech entitled "The Heart of a Gamer".
At this point there is only rumor and speculation, so it's best to treat it as such. Please wait for an official announcment/comment from Nintendo.