Interesting you would rather see the exhibits repurposed for orangutans. I assumed that with access to the adjacent island there would be enough space.
That would be enough space for another female and resulting offspring, but I'd like to see the complex expanded even more to hold more than one breeding female. That's just my personal preference.
It’d be nice to see Melbourne Zoo hold a colony of orangutans. Perth, Auckland, Taronga and Melbourne all used to hold decent sized colonies and while the trend has been to downsize, they remain a charismatic species that are even more engaging when displayed in large numbers.
Being a semi-social species at best, multiple small exhibits would need to be utilised with options for rotating them through a larger exhibit/high ropes.