Can they afford the paper to print the new banknotes? Or are they just gonna get some folks with really strong magic markers to work on the old ones?
That is a great question. Currently Venezuela can’t print bank notes fast enough so cash sells at a premium in the country. Pretty easy to eliminate zeroes electronically.
There are cases where the gov’t does overprint old notes either to add or eliminate zeros. Google Transnistrian ruble or Bosnian Dinar.