No idea. However, it doesn't mean they won't ever start a new group in the future.
They probably won't do anything for a while. They've already said they're rotating the geladas across to where the macaques were (which they've done a few times before now) and are going to the leave the geladas' original enclosure empty for now to recover.
Although an increase in space of any quantity for any enclosure is technically an improvement, I think merging the Barbary sheep enclosure with the small space occupied by the Parma wallabies would be negligible. A far more impactful improvement would be to merge the enclosure with the space behind it, i.e. the space between the otters and the back of the Queen Mary restaurant; space that is usually wintered by the Cameroon sheep. The problem with that however would be the familiar issue of getting planning permission for installing the required new fencing (and perhaps toughened glass), since the Queen Mary restaurant is a listed Tecton.
Takin or Barbary sheep would look great in the large, banked enclosures either side of the chairlift. However, if they were to be rotated with the geladas then both enclosures on both sides of the chairlift would need to have large new housing and a new hardstanding area constructed. There would be the space to build this for the right-hand enclosure, on the site of the fairground, but definitely not on the left-hand side. The new housing/stabling would need to be extremely multipurpose to be able to adapt to accommodating both primates and ungulates at different times. Also, you'd have to have a way of transferring the herd across from one side to the other. In addition, the whole point of rotating the geladas from one side to the other is to give the grass in the enclosure they were in a chance to recover, so swapping them with animals that will do just as much damage by grazing on it defeats the whole object.
It's a nice idea but I think realistically the zoo would just be making life difficult for themselves.
Whatever species the zoo brings in to rotate between the two enclosures with the geladas needs to one that is mostly terrestrial, can cope with the steep terrain and exposed hillside, suits the existing housing and fencing, and won't damage the grass.
In a way it's a pity that the zoo also has the bachelor group of geladas, otherwise they might be able to rotate the large breeding group of geladas around 3 different high-quality enclosures, which would be ideal.
Anyway, a wishlist/ideas for the future thread, which was made for lengthy discussions of this nature, can be found
here.