Alby_da_Wolf on 18 January 2015
September 2016 at earliest, because the new tech won't bring real savings in its first year, or in the best case, not enough to justify an early redesign. Until the new chip cost drops enough, economies of scale and production process refinement of the original model will bring more savings.
Also, the Slim model usually provides a big sales boost, it's better to already have a large enough existing game library and additional big games launches for the new HW launch period to maximise its effects. Moreover a big sales boost requires careful planning of production and logistics, to avoid wasting its full sales potential or damaging profit margin.
