The Collared peccary can potentially live into their early 20’s, so Melbourne Zoo may look at transferring them to a wildlife park if they’re still alive when the space is needed to create a Brazilian tapir exhibit. To be honest, I wish they’d done that as soon as they decided they’d be phasing them out, so somebody else could have bred them and we wouldn’t be losing this species from the region.
Melbourne Zoo could potential hold a 1.2 breeding group of Brazilian tapir across the two exhibits. Females are semi-social (especially when related), so ideally multiple founders would be imported within the region, with Melbourne receiving a founder female and her first generation daughter (to breed with an unrelated founder male); or a breeding pair with the male swapped out once female offspring is produced.
Knowing Melbourne I think they'll wait until the Peccaries die, and leave the Tapir enclosure empty in the meantime.
Capybara would actually suit the enclosure too. I think they're a good secondary option if Melbourne don't wish to reimport Brazilian Tapir.