From what I've seen trio litters are usually predominantly one sex (male or female) too, so this is a very rare occurrence! It'll be interesting to see how the dynamics play out and the individual personalities of each individual; Nilo's offspring historically have been quite cautious and quiet cubs, not really the outgoing type.
I believe the next step should be to breed from Asali, but it seems like Werribee likes to have a year in between each litter (not exactly sure why). Anyhow, we can probably expect a litter from Asali next year if anything. With an additional empty exhibit that they have in their hands they can actually afford to breed without having to worry about placement issues down the line.
I was told the year long gaps between Werribee’s litters was due to the dens being unable to accomodate two litters at once, but it was surprising to see them undertake introductions of three month old cubs to their 12-15 month old half siblings and potentially risky.
On the plus side, males usually outstay their welcome around 24 months, so two litters born a year apart could see males from both litters transition out of the pride together - potentially into the second exhibit you mention.