So if we can't keep mages, toplaners and junglers out of botlane, how about...

... simply making supports able to go to other lanes without being either abyssimal weak or brokenly overpowered (Hello )?

I regulary see Annie supp, Vel'Koz supp, Morg supp, Naut supp, etc etc. Literally every champ that can offer CC and/or poke is able to do that play that role, sometimes even more efficient than an actual support champ. Sure, I guess this would require a roster wide update, but some of these champs are like REALLY old.

Sona's kit is so simplistic it's the main reason she gets bludgoned by the nerf bat whenever she is even a little strong. Leona's kit is lame and binary (go in or not go in, that's the question) and does in no way reflect her lore as a badass sun-warrior. Alistar is getting nerfed AGAIN because Riot wants to keep that outdated combo... I'd rather see Ali with something like a Sion ult where you run and crash into the enemies like some kind of wild bull. Karma... well, since the rework she's be completly without any personality or character apart form being "staple utility mage champion #43". Soraka needs an identity that goes beyond being a boring heal bot - Maybe focussing on her E would be good start. Janna is still a shield-bot, but does that so well she also got nerfs yet AGAIN.

Here's what you should do Riot: every tank support should also be a healthy and viable pick for either top or jungle.

And every mage support should be able to go at least into midlane without either abusing certain parts of their kits or being stomped by default by literally any other pick.

Also, by that you make this class of champions a tiny bit less team depedant - one of the reasons no ones is playing support right now. If you don't queue up as supp or fill (which also means upp in 99.9% of all cases) the waiting times are atrocious...