It's a McConnell rule. If she somehow makes it to Jan 20, 2020. We'll have to wait until Jan 20, 2021 to confirm a new Justice. Moscow Mitch will insist on it.
Actually it is the Biden Rule, you know that of course. And it only applies when the Executive and the majority party in the Senate are different parties.
Ruth Bader Ginsburg is very ill yet, she hangs on trying to protect her extreme liberal slot in the US Supreme Court. She should worry about her health and her life as old as she is. Spend time with her family. That is way more important than being a die hard extreme liberal partisan. Much like Elijah Cummings still being made to sign subpoenas on his death bed. Sad but, true.
Republicans better hope the old gal stays on this side of the grass. If she kicks anytime between now and the election there's no way the seat gets filled. More than that an opening would give the dems something to rally around as that empty seat will serve as a catalyst. If the dems were smart they'd convince her to announce her retirement early next year for an exit just prior to the election.
Since she already has one foot in the grave anyway, I don't see how that will make any difference. They can use her upcoming vacant seat as a rallying point with or without an announced retirement.