Riot Games teased the upcoming patch 13.4 in their usual patch preview. Senna, Ahri, Viego, and Orianna will be buffed, while Amumu will receive the second nerf in a row. The developers will also decrease the experience gained from kills. Matt "Phroxzon" Leung-Harrison revealed these changes on Twitter.
He explained that patch 13.4 would be dedicated to balancing ranged vs melee supports in the bot lane. Also, they will optimize jungle pathing, "addressing early snowballing and flattening some healing."
Patch 13.4 will come out on February 23. Spideraxe already revealed the featured support item changes; you can read the details here. There are reasons to assume that the next champion, Milio, will arrive on the next update after that since he was teased on PBE previously.