Okapi are one of my absolute favorite species, but I would have to concur that they would not make for a standout exhibit or a be a real drawcard replacement for the zoos phasing out elephants. They do really well as supporting acts in a larger African Rainforest story, but the general public will not consider them the stars (although they'll always be my stars). I will say, I also wouldn't go as far as to say that bongo would serve any better as a standout/stand alone exhibit, as while bongo are also absolutely stunning and are exhibited in herds, they are even less active than okapi. I have worked with a lot of bongo in my time, and they are truly some of the laziest animals (and messiest, but that's another story).
Okapi are absolutely striking, yes,and their strange appearance does tend to hold an audience more than many hoofstock species, but the general public still give them little more than a passing glance after they briefly gawk and say "look at that half-zebra, half-horse" while trying to figure out how to pronounce their name. While I will say that okapi are not always as shy and reclusive as people like to make them out to be (I think this assumption largely comes from the well known fact that they were not known to western science until so recently) -- they are, in fact, usually one of the most tractable of hoofstock species -- they are still hoofstock, and primarily nocturnal hoofstock at that. They will almost always spend the majority of their day standing in the shade, browsing, and even the most tractable individuals can be quite skittish, and it is usually really random things that set them off.
Okapi do also not generally mix well. I would not mix them with anything larger than a yellow-backed duiker. A male nyala killed an okapi in a mixed-species enclosure at the Blank Park Zoo here in the States. Birds usually do well (okapi usually leave them alone, as opposed to other hoofstock species), and I know Doue in France mixes theirs with owl-faced guenons in a large aviary, but I'm not so sure I would want to mix them with more boisterous colobus. On rare occasion, multiple okapi can be housed together-- San Diego had up to five related individuals sharing an enclosure and the Species Survival Center in New Orleans has three (1.2) individuals living together in a 22-acre enclosure. It just depends on the personality of the individuals. Individual okapi have very distinct and very differing personalities. Breeding pairs can sometimes be housed together permanently, but a lot of the times they are too aggressive to be housed together outside of breeding (okapi courtship in and of itself is actually quite aggressive). I do not think that multiple intact males could be housed together long-term -- I have personally worked with males that would try to attack each other through fencelines.
At the end of the day, I think it is important for us to remember that our perspectives as zoo and animal nerds are not going to be the same as the general zoo-going audience. To most of the zoo-going public, to the families with children that have probably never heard of an okapi before, even if the okapi is the only okapi in the country, they are still probably only going to think of it as a weird zebra-horse. This is, of course, truly unfortunate, as okapi are such unique animals with such a unique story to tell, but it is what it is. This absolutely shouldn't deter a zoo from wanting to exhibit them, as you never know who will be inspired by them and it's important to tell the story for those who will listen, but don't expect an impact because they would have an impact on us.
So what would make an engaging okapi exhibit? In my opinion, making the okapi a part of the greater story of the African rainforest, showing them as a facet of that habitat, alongside the great apes, monkeys, birds, and pygmy hippos, creates more impact. Both the San Diego and Dallas Zoos have a demonstration area where keepers bring an okapi over to feed while they give a talk about okapi, and it is during these demonstrations that I have seen the public the most engaged with okapi. Using sightlines to create the illusion that the okapi is in the same space as the other animals also creates an engaging display. This is also a facet of both the San Diego and Dallas Zoo okapi enclosures, both being placed behind their Nile hippopotamus enclosures.
