In addition to those mentioned above:
- A high quality Philippines field guide with up-to-date taxonomy,
- A West Africa field guide matching the quality of the Stevenson and Fanshawe guide to East Africa,
- I hope Phil Gregory's New Guinea guide meets expectations - I have found some of the illustrations in Pratt and Beehler 2nd edition surprisingly inaccurate in the field,
-I think there is zero need for another Australian field guide. While none of the available options are great, Australian birds provide relatively few identification challenges.
- I'm not sure a single comprehensive field guide for Brazil is all that desirable, for visiting birders at least. The WCS "biome" guides published so far are pretty good, and if you are doing a trip to the Atlantic Forest, for example, it's nice not to have to wade through dozens of e.g. Amazonian species.