I'm so ecstatic for this.
I love how the names of her abilities are actually making way for story, or at least speculation of the mysterious Void. What does being a queen in the Void actually entail? What or who are the Xer'Sai? What is the Void structure/ecosystem like? What is Icathia in relation to Shurima?
We could be seeing some lore-love to the Void sooner rather than later.
And if we're theorycrafting, I'd like to point out something I thought was rather interesting. Considering the retcons to Skarner and Shurima, could we be seeing a tie-in with the Brackern to the Voidborn?
Rek'Sai seems like she's been in Shurima for quite some time, and Skarner has been moved to be a creature of the deserts there. Has anyone noticed that Rek'Sai's color scheme is very similar to Skarner's - they both have purple, and that could just be an artistic style-choice unrelated to lore, but the shade of purple Rek'Cai has is noticeably different from Kha'Zix, Vel'Koz, Malzahar, and Kassadin's. Rek'Sai also has blue accents on her, again that are very similar to Skarner's. Considering the retcons, what if these "Xer'Sai" are or are related to the Brackern, and Skarner could be a possible descendant of the Voidborn?
A theory I have is that Rek'Sai is a leftover from the Void's earlier invasion on Runeterra, and that she survived & adapted to the deserts of Shurima after the long millenniums. It is quite possible that in that time she somehow produced offspring, and as generations passed, evolution took its course, adapting a portion of these neo/Runeterran-Voidborn into the Brackern.