Very little really apart from heavy log structures as platforms and ladders for them to climb on, plus some planting if I remember right.
I agree it would be unlikely to see Pandas in such a simple conversion nowadays. It looks as if Edinburgh's makeover has really only left the basic structure of what was there before.
I was in the ZSL Casson/elephant pavilion just a couple of weeks back-and thinking how it really doesn't lend itself to anything much on a scale less than the Elephants and Rhinos it was built for.