My sense is that this is mostly a gimmick as far as curbing the illegal economy is concerned. (1) Illegal cash is a fraction of illegal income which is a fracti

My sense is that this is mostly a gimmick as far as curbing the illegal economy is concerned. (1) Illegal cash is a fraction of illegal income which is a fraction of illegal wealth. Destroying a further fraction of that cash will not be a huge setback to the illegal economy. (2) Some (and perhaps a lot) of the illegal cash will get laundered through family and friends and deposits by businesses which operate in cash and do not have to keep detailed accounts (3) This is a game that you can play only once. Once people know that such currency 'reforms' are possible, illegal transactions will move to alternatives to domestic currency. Dollarisation of the Indian illegal economy is one possibility.