If the DS Lite was still in production, I'd say it could've had a good run for another couple years, I think the main problem is how enticing it is to just get a 2DS or regular 3DS for a step up of what, 40 USD?
Bet with Einsam_Delphin: http://gamrconnect.vgchartz.com/thread.php?id=172355&page=11