I have no idea, but my estimate as to what will happen is below.
An excerpt from my 2012 review:
The zoo has two aging female elephants (52 and 60 years of age) that were obtained from Ringling Brothers Circus. The outdoor yards are sufficient for two elderly elephants but with the new AZA rules coming into effect in 2016 the zoo will have to decide what to do with the pair. The current exhibit is simply nowhere near large enough for a modern habitat with a herd of elephants, and in truth it would have to be renovated for white rhinos as that seems to be the species that are almost always replacements when zoos phase out their elephant program. My guess is that one of the elephants will die before the deadline and the remaining animal will be allowed to remain on-site until it also passes as moving senior elephants can be a risky business.