Over a long period of time (say 10 years) I could see this working as intended. All current .com domains would probably have to get their identical .xxx domain

Over a long period of time (say 10 years) I could see this working as intended. All current .com domains would probably have to get their identical .xxx domain for free however so they could re-direct traffic to their new .xxx domain. Why would they do this? I don't know.