My take:
1. Markhor - it's very iconic, would bring representation to Central Asia, and give us a desperately needed ungulate for Himalayan sections
2. Gelada baboon - A baboon is necessary to complete the African roster, and since the Arid pack missed the opportunity to include the Hamadryas baboon, this pack seems the best opportunity to me
3. Andean bear - to fill up the seemingly madatory carnivore slot, and give South America one of it's more demanded predators
4. Musk ox or Takin - both seem popular, yet I don't think we could get both in one pack
5. Golden pheasant or Himalayan monal - would round up the asian roster a little more, and might be doable as clones from the peafowl rig
6. Alpine marmot - a cold climate rodent that would complement the european roster very well
7. Goodfellows tree kangaroo - given it's exclusion from the Oceania pack as well as the Forum communities recent discoveries about its inhabited biomes, I would gladly see them in this pack
Exhibit: jackson's chameleon (found at great altitudes of up to 3,200 metres) or the veiled chameleon (found up to 2000 metres), with the latter one being slighlty favoured by me due to it being from Arabia, which could still use some representation.
Honourable mentions: Francois Langur (they live in limestone cliffs and are endagered), lesser rhea (lives at the Altiplano plateau in the andes) and the european mink (critically endangered semi-aquatic animal from the pyreneans in europe)
I have to admit that I want a highlands pack the most, because it could be one of the animal packs that gives representation to many different areas.
Genuine question: Is the Pallas cat really that desired? I feel like it would be a bit of a wasted slot considering the many non-feline alternatives, but maybe that's just my opinion.