This sounds ridiculous. I kinda understand not INCREASING THE ISSUE... which would look like not allowing payments to older addresses.

But actually no. Even that is ridiculous. Ever heard of timelocks and pre-signed transactions?

So what, we're basically issuing a new currency and demanding everyone trades their old ones for new ones. (Remember utxos just get burned for new ones).

Anyone with cold storage now needs to dig it all out and start fresh by a certain deadline. Nevermind how hard it could be.