Well, once abortion is confirmed to be murder by the government, obviously all previous offenders would be grandfathered in. The law would only apply to new offenders. You can't prosecute somebody for something that wasn't a crime at the time they did it.
You still can't get past the fact that it's never been punished as murder, even when it was illegal. Why would the punishment be so much higher now? And why is legislation still being written that just mandates fines or a short jail sentence for the doctor, and is specific about NO punishment for the woman? That's exactly the way the Partial Birth Abortion Act, currently under consideration by the Supreme Court, reads.
Why is that, if it's murder?