I don't see how the handheld market would be diluted? The DS was released back in 2004, I mean 2006 has been 2 years later and I am sure people are already eager for a new handhelf system.
Not to mention the new battery a US/Israeli Company is making that will allow something to run for days...
Not to mention the new battery a US/Israeli Company is making that will allow something to run for days...