Senna has been dominating the support role in League of Legends, and a lot of that comes down to her diversity and options.
Right now, she regularly goes Frostfire Gauntlet but Riot want to move her away from such a tanky build, especially when paired with Grasp of the Undying.
The option seems to be to turn to Lethality or AP, although I can only see the former happening since her kit revolves around AD too much for AP to be viable.
On top of that, we also seem to be getting some changes to tank items. Specifically, Warden's Mail/Frozen Heart and Warmog's have been called out as needing love, while Thornmail is noted as being too standard.
This won't necessarily mean nerds to Thornmail and Bramble Vest, but hopefully buffs to the other items to make them more viable.
They've called out 11.11 as the patch for it, so we have two weeks before it would hit live. The usual warning of it may never get shipped, or at least not for this target, obviously applies.