The mini-LED iPad Pro is rumored to be delayed until 2021 because of supply issues. I think we can assume the MBP will be even lower on the priority list for the mini-LED upgrade. And I don't think Apple will wait that long to launch the Ice Lake chips they have ready to go, hell, Intel already showed off Tiger Lake at CES and it's coming soon.
That leads me to believe, the next refresh will be Ice Lake, Magic Keyboard, and normal LED screen, only question is if it stays 13.3" or increases in size to 14.1" just like the 16" did. The refresh after that, late this year or early 2021, should be Tiger Lake and mini-LED I think.