I doubt Ceyla is reproductively viable given she's in her late 40's and hasn't produced a calf in 17 years.
It'd be a shame to break up a matrilineal line, but for the sake of a cohesive herd, it could be worth sending her elsewhere and merging Farha with Indi and Chandra (if possible).
I'm confident this isn't the end for Zurich breeding. Many European zoos have had set backs on this scale and worse and persisted
Ceyla has offspring in the UK (and Australia too) through her son, Upali, so this is why she hasn't been bred following Fahim's birth in 2005.
I'm not sure Zurich will be willing to do this. Until at least Farha has some children (daughters) as support.