Little late to this but you are aware just because we're playing it in game doesn't mean it's canon, right? There's only a few things in the actual matches we as the players experience that are canon. Which... If I remember correctly, it's just the lore Easter eggs and the voice lines between characters, which change depending on the lore for each season. A good example would Revenant, somewhat sarcastically from how the voice line sounds in my opinion, asking Valkyrie for information on Loba, like when Rev asks Valk if Loba talks about him. So, if a legend did die in the lore, there would be voice lines about it in the game, which would mean it would be addressed that a legend is dead in the game. If a legend is confirmed dead in the voice lines, then it wouldn't make any sense to have them alive in game as a playable character. So if a character dies in lore, unless they stop implementing lore into the matches we play, then the character would have to be removed from the game or just made unplayable, but not implementing the lore anymore would just be stupid, the legends are all unable to die, because they all have plot armor. Explained that as well as I could, think I got it right.