Regarding the move, I wouldn't say no chance. Oftentimes I come across a move whose data will work with a 2k20 move. Its usually by a stroke of luck to find the right one.
No one knows if we'll be able to access the files by then. I will have loved to be working on porting the DLC Moves and entrances by now .
Regarding all the 2k20 moves not working in 2k19, I will say that's expected. A lot of 2k19 moves will not work in 2k18 for instance. Its much harder backporting moves than porting moves from previous games to a new game. The reason for this is, when changes are made to the gameplay and animation engine for a new release , the new moves contain data which the modified game engine supports. Quite a few wouldn't work as the previous game didn't have these features.
As I mentioned in a previous post, I'm not that optimistic we will be able to retrieve data from the game files. If we can retrieve them, Ill work on porting over what is possible.
2k20 arenas can't be ported to 19 as the formats are different . 2k20 doesn't use the pac file format and this makes it impossible to copy assets to 2k19 like we can do with 2k18 or 2k17 files.