About rework and Super Smash Bros
Reworks have been dividing the community ever since. Those who like rework and those who don't.
So, I'ld suggest a simple suggestion; like it was done for Link in Super Smash Bros. (SSB). In SSB there's a "Young Link" and a "normal" Link.
Translating this into League of Legends would mean making several "stages" of a character available. Less confusingly: There's a rework version and an old version available for picking. Those Two would have different names to distinguish them.
This would reduce the conflicts between fans of the "old" and the "new" champion and raise acceptance for champions.
It could also be interesting lore wise - a story could explain how and why the champion changed from what he was, to what he has become and why, with relatively similiar roles but completely different kits (e.g. Sion)