These are some possibilities I have came across by while searching for update news:
Corn
Change Some Texture w/out Packs
Spikes

They say ALL Minecraft mobs are going to have new animations to show they are hostile.
They are So far making new animations for that are confirmed:
The Skeleton [Non-Aggresive = Stand straight]  [Aggresive = Bow pointing out toward you]
EnderDragon [you know revamp and all]

Proof: Here

They are making more boats I'm guessing the other types of wood as well.
Boats are aswell being redone to not break as easy and stuff like that.
I mean you cant
Boats Confirmed:
Birch

Entity's can join you on a boat.

Proof: Here 

Dual Weild'ing has been CONFIRMED!!!!!
Well..Somewhat.
There will be 2Arms now instead of 1.
How it will work: 
Enderpearl left hand sword right hand both will work.
Sword on left and right hand only right will work.
You CANT use 2 weapons at once. ONLY items.

"Lefty Option" Confirmed!
Are you a lefty? This is the option for you!

Swords Can't be used to block anymore.

Proof: Here and Here

In the New Generated Structures this is what we have CONFIRMED:
A new type of dungeon with new Blocks and Mobs.
It is related to the “new dark colored block”
Added support to rotate and mirror structures.

Proof: Here

New Ranged Items are: Quivers (Arrow Holders), ATLEAST 4 new types of arrows.
New Defence: SHIELDS
The Textures are originally from a game Notch abandoned called "Legend of the Chambered"

ARROWS CONFIRMED:
Spectral Arrow [yellow looking arrow]

Proof: Here

There is now "Pressed Dirt"
This will be used as a new path for minecraft.
Different Size than all the other blocks.

The Ender Dragon is getting a Revamp.
"To Be more like the Xbox Version"
They're trying to make him harder and have new abilities Like "Ender Breath".

They as well talked about how they want to make the Ender Dragons EGG more important.
We don't know what yet but I think:They might make the EnderDragon hatch from it.
Reason For Thought: They talked about "It coming back after it dies".

They might make Dragon A GIRL based on Seed.
Proof: Here and Here

They might or might not add "Multiple Boss Bars.
If there is more than 1 boss around you we will see 2 or more "Boss Bars".

Proof: Here

In the QR code They confirmed Minecraft 1.9 will be called "The Combat Update."

Proof: Here