I think at this point it would be useless producing new units meant for the Japanese market, yes, but naturally you're going to sell whatever stock still leftover somewhere.
I think they should sit it out until the coming holiday and discontinue it January 2014 in Japan. They can keep it around one more year after that in the west if the sales remain as they are. Exactly 10 years after (the western) launch would be the perfect farewell time for the DS.







