I'm thinking it'll be early October, but it could definitely be mid-late September.
Guessing the theme is a bit tougher. Anything from hopes for the popularly requested avian or marine pack, to biomes ranging from temperate, mountains/highlands, rainforests, drylands or even region based like Oceania. And of course, the noctural pack or some other "new" theme.
My hopes are either Avians or an Oceania revisit. My guess is probably something temperate related, or a new theme (nocturnal again is gaining popularity). This last DLC really showed us that Frontier is creative in regards to packs and not just limited to biomes or locales.
An Oceania animal pack would be AWESOME.
I dont´t know why, but oceanian animals are very beautiful and extrange, i love them. My pack would be this:
Oceania Animal Pack (13,September)
New animations:
-Tasmanian devil (Star)
-Goodfellow´s tree Kangaroo (Popular animal)
-Brown Kiwi (Pack surprise)
-Common Wombat (Popular animal)
Simple animals
-Emu (Similar to cassowary)
-Yellow-footed wallaby (Similar to red kangaroo)
-Little blue penguin (Similar to African penguin)
Exhibit
-Thorny devil (Popular animal)