No, it’s not nearly the same. If a totally different person is on there, you’re just not going to win the “legal” argument that “No, you’ve voting for an elector.” That’s a Ted Cruz-type move, but it wouldn’t hold up in the court of public justice-—even among a lot of Dems. So if state legislatures (not OH, cause that’s R, not AZ cause that’s R, don’t know right now what FL and NC and VA are, but right there are the only ones you’d have to worry about) do “correct the names” of the electors, the suits would claim that in fact people voted for different electors already.
You cannot legally get around the fact that VOTING HAS ALREADY STARTED and Bush v. Gore will be the yardstick against which this stuff is measured.
The Constitution states that federal elections must be held on the same date, and we settled on our current date in 1841 (I think). This is why a Florida revote was constitutionally impossible in 2000. I even question if early voting is constitutional, but that's for the courts to decide if a challenge ever arises.
As to whether Hillary is replaced because she dies, becomes a vegetable due to a stroke, or leaves for other reasons of health, the legal situation is the same even if the political situations are different. Because of the wording of the Constitution, I have a hard time seeing how any body other than a state legislature would have jurisdiction to decide matters, no matter how many scofflaw courts, like the Florida Supreme Court, chose to claim jurisdiction. If I remember correctly, the Florida legislature had a slate of Bush/Cheney electors ready to go if the Florida Supreme Court continued its obstructionist behavior by the time the Safe Harbor Date came around.
Admittedly, law is one thing and politics another, but I have problems with your scenario. From a legal perspective, it's not intuitively obvious.