There is a big difference between what "would like to see" and what "is actually realistic". I would rather go for the last option.
Elephants - aka what status the larger import (perhaps they can take some of those redundant Indian zoos eles if the CZA go through with that bizarre/Age of Stupidity plan) - and put the elephant breeding center on a firm setting.
Some more and rare hoofstock be nice (allthough I feel that aridland/steppe type hoofstock are not applicable here). Okapi? Babirusa? Anoa? Alfred's deer? Visayan warty pigs? Malayan tapir.
Carnivores: Amur leopard, clouded leopard and snow leopard. Pure-bred lions, an unrelated Siberian tiger male and cheetah.
Birds: obvious lacunae in collection (maybe they need to look at Safari Beekse Bergen in Hilvarenbeek for pointers): pelicans, ibis, spoonbill, flamingoes, storks, some wading birds (Pluvialis, Vanellus, Recurvirostra et cetera), wetland birds (white-headed duck and other rare Mid-European/Mediterranee ducks). African savannah bird house: hornbills, cranes, secretary bird, shoebill, storks (in particular Mycteria ibis, saddle-billeds, Abdim's and blacks), hammerhead .... S.E. Asian rainforest birds (hornbills, catbirds, Garrulax ...., peacock pheasants).
Some more primates: lemurs (they hold brown and red-bellied only), langurs, colobus, some mangabey and cercopithecines.