Well, that’s a bit different from your OP, which suggested that the old bills would be “worthless” after six months. Now you’re suggesting a special process to exchange the old bills, as in the examples in the UK and Sweden, discussed earlier. That doesn’t sound like de-monetization to me.
But in any event, what does your proposal accomplish that isn’t already dealt with by the Bank Secrecy Act, which requires disclosure of cash transactions/deposits of over $10,000? If a drug-dealer shows up at a bank with a suitcase with more than $10,000, even nice, crisp new ones, the bank has to report it to the feds. What additional safeguard would your proposal add?