Toyota and Honda are apparently investing quite a bit of money into making it sustainable. Again, i have not seen any data out there to claim that Toyota is throwing these used batteries in the dumpster at Walmart. As the article clearly stated, NiM batteries from Toyota and Honda are fully recycled at the end of its life.
Again, FYI:
"Nickel metal hydride batteries are benign. They can be fully recycled," says Ron Cogan, editor of the Green Car Journal. Toyota and Honda say that they will recycle dead batteries and that disposal will pose no toxic hazards. Toyota puts a phone number on each battery, and they pay a $200 "bounty" for each battery to help ensure that it will be properly recycled."