FFG has colour coded each wave/set which makes rotation as easy as following the colours of the boxes, once black leaves a format all of the black boxes leave.
Trilogy - Current colour.
Standard - 2 Most recent colours and any pre-released items from the third that come out before the core set (2 player box for example.)
Infinite - All cards.
So no, cards like ancient lightsaber won't fall out of rotation until the third colour boxes comes up. Unless for some reason you just play trilogy.