Will the Legendary Snowball/Axe type event ever return?

For those who don't know,

Legendary Snowball - Snowdown 2015, obtaining a legendary skin unlocks an additional Mystery Skin. If the Mystery Skin turns out to be legendary or better (shit odds, but you never know), you get another Mystery Skin, and so forth.

Legendary Spinning Axe - April Fools 2016 (Draven day) event, same as above.

*At the time of Legendary Spinning Axe, this is confirmed to also apply to skins unlocked through hextech crafting.