If i can just add my 2 cents, imho they should go like this..
Old rewards can rot to hell.. wathever..
For a new system i think they could leave top1, top10 and top100. They should get only titles and trophies or plates (i mean a furnishing item like). Beside that should exist a similar battle pass sistem that let you achieve with hard work mounts and glamours..

what do you think? i think that could be a nice compromise..