A feature I like to call "The Legacy Reserve"!
So I'm sure ALL of us have quested for a skin we've simply waited to hit the shops again for MONTHS, maybe even a whole YEAR. But our only luck between these times is to get lucky enough to unlock them in a chest. The sad part is, we were JUST about to get paid when the cutoff date for the skins to be available was but only the day right before.
I propose "The Legacy Reserve" feature. This will allow users to select ((2)) skins from a legacy event to be reserved for an additional week. Lord knows I've waited forever just for Conqueror Karma to finally arrive back in the shop. This isn't an extremely difficult feature to implement either, nor does it affect Riot's profits at all negatively. Of course they don't!
This is just what I recommend and I'd love to be able to see it happen!