Yo, since we all know this game is on the decline i think i might have an idea to bring some of old players or bring back some of the nostalgia/excitement for the current playerbase.
Lifting (some) permabans. Yes, even though we should disprove of toxicity and we know that accounts are banned for a reason, i think the ban system could use a bit of refreshment.
So, what do you do after your beloved account gets permanently banned, and indefinitely locked? You got two options, stop playing the game altogether (for at least a while), or make/buy a new account.
When you make another account, people usually just fall into the endless cycle of making/buying throwaway accounts, and then the bans seem to not matter at all. After losing your first, original account with hundreds of skins you might not really care anymore, and keep getting banned on new accounts since, well, they are really easy to come by.
Now, i think there should be another punishment before permanent. A season ban. For example, let's say your account was banned during season 7. The account is locked until season 8 begins, and you have a chance at redemption. One more strike and THEN you should be permanently banned.
Maybe that last chance of playing on your beloved, original account just might do the trick and help you stop breaking the summoners code.
Just revive and unban some accounts in bulk, one-time, like accounts banned before a certain season (s7 for example) or accounts that had a significant playtime or transaction history.
Maybe when old accounts get unbanned, more of the players that have quit might come back to the game.
Giving another chance doesn't always pay off, but i think we've given Riot plenty of chances to redeem the game to the way people used to love it. This might just be a reviving factor for many, many players.