I would much rather wait until summer for Pool Party Taliyah than get a fire or gem themed skin next patch. Then Next year who knows, maybe Taliyah's popularity will spike after a small update or rework and we could get a Jade skin in February and a Harrowing skin in October. Maybe we could even see a Victorious Taliyah if she gets that popular. And again, I would much rather have an event theme than a one off, especially for Taliyah. Other champions could make much better use from a one off skin.
Really think, what kind of skin would best suit Taliyah? The first thing that comes to mind is surfer Taliyah, then after that a grave rider Taliyah, then Jade, school girl, and then something like crystal or obsidian. And I do not see Taliyah getting a God, Dreadnova, Chemtech, or Lancer skin any time soon.