According to an article in the Times of Africa dated 21 June 2011, the Bank of Zambia is contemplating replacing the paper 500- and polymer 1,000-kwacha notes with coins, and issuing notes larger than the current highest denomination of 50,000 kwacha. The bank is also considering using polymer for a higher denomination than the 1,000-kwacha note. Nothing is official yet, but the new measures could take effect in 2012.
Courtesy of Richard Miranda.