Lean D for now. Democrats would be incredibly stupid to take this race for granted, and I believe there is a lot more "upset" potential here than in PA. Running a more "Trumpist" wave insurance candidate and not some random boring "generic Republican" seems like the best option for the GOP in MI IMO.
That being said, I think there is an 80%-85% chance that this race is a very easy double digit win for Stabenow and maybe a 15% chance or so that it goes down to the wire. Nothing in between. That's just my gut feeling, and I could be wrong of course.
I think this race is safe D (regardless of what Kid Rock does) and the PA Senate race probably is too, tbh.