Assuming we're correct about the bighorn sheep and coyote, I think the North American deserts and grasslands could definitely go blue. For North America, I still need the black bear for the eastern forests to turn blue for me personally. Also, an American flamingo is better than 0 birds, but it has no range in the Nearctic realm. The everglades is considered neotropical. I still think we'll eventually need the bear, ~ 2 birds, maybe a musk ox, and maybe a deer. There's more I'd love, but I think other regions are due a chance to shine for the most part.
I think the rhea could turn Patagonia yellow or at least orange on its own, but we still need the mara for green. For me, the Chilean flamingo would make Patagonia a very solid yellow with the rhea and blue if we get the mara as well.
The saki is not enough to pull the South American tropics out of orange. A coati and an American flamingo would help a lot, but together, they still wouldn't be enough for me. Another monkey might make me consider yellow, but I'd still want ~2 more things (another monkey, bird, and/or ocelot/oddball) to confidently call it yellow.
