The TFT Carousel will return in Set 18
via polygon.com
Short excerpt below. Read at the original source.
Teamfight Tactics (TFT) is changing up the formula with Set 17: Space Gods by removing a foundational piece of its in-game experience, the Carousel. The Carousel functioned as a comeback mechanic for players, giving low-health players first dibs on a rotating shop of champions and items, while high-health players would have to wait their turn.