So consider these solid sources, who are reporting anything that they can, or have seen.
via anonymous sources on Faeit 212
Fire warriors will be a dual kit.
No new sub-races for Tau (Kroot & Vepsid only), no model change for them.
I believe Tau to be a three week release
I saw the new Tau codex, unfortunately not the content but the front and back cover, front cover looks like the old codex with a crisis suit.
The new photo on the back cover is very interesting, everything is painted in white with:
1. New XV8 crisis suit, with new shoulder guard similar to current fire warriors and potentially new jetpack
2. New XV8 commander, with a new jet pack (may be the old one, but the jet pack and pose looks different)
3. New Ethereal (I think)
4. Some Tau specified terrains, sort of a watch tower and a sentry post kind of thing.
5. A new suit class, I think its larger than XV88 but smaller than Riptide, with the head of a stealth suit, unsure of the weapon load though
6. A new suit at the back of the photo, may be a dual kit with the above
7. A new massive suit, larger than Riptide! very bulky with a shoulder mounted rail cannon of sort (very big) and having very large missile pods instead of arms (kind of like a bastard child of Tomahawk from Macross and Zssa from Gundam ZZ, but no arms though)