Suggestion of a fun game mode to allow us to replay champions that have been removed from the game

The game has come really far in the last several years, particularly in terms of the competitive experience, and I completely understand the necessity of updating certain champions with particularly outdated kits and mechanics. However, regardless of their flaws some of the most fun I've ever had on league of legends has been playing champions such as old Sion or old Evelynn (the original - I'm aware she's been reworked a couple of times).

Would it be possible to have a new, fun rotating game mode or even custom game where some of the removed champions and items can be played again? I can see this as being really fun and nostalgic for a lot of long time players and would give newer players the chance to experience champions, items and metas that they missed out on.

TL:DR - Please give us the opportunity to replay some of our favourite champions (and items) that have long since been removed from the game.