From what I've been able to gather from the many sources on the interwebs, these are possibly some of the announcements we'll see at BlizzCon 2010! Enjoy!

- The 5th Class! (Confirmed)

- The Talisman Customization System! (Semi-Possibly Confirmed)

- Skill Rune System Preview! (Most Likely Confirmed)

- Further Details on the Artisan System! (Very Possible)

- Details on a Possible Trading / Item AH System!

- Charms Returning to Diablo 3! (Possibly More Information on This)

- Other Modes of Play! (Just Guessing Here)

- Estimated "Big News" Announcements for Diablo 3! -

- PvP as a dedicated E-Sport!

Estimated "Big News" Announcements as "Wishful Thinking."

- Beta Start Date Announced!

- Release Date Announced! (This one is impossible!)

Take your pick, feel free to add your own estimated predictions, but I'm expecting at least a 70% reveal of the game and all it's systems that have been solidified, if not 90%. (Arbitrary Percentages are Arbitrary.)

---

Q u o t e:
As of yet we have heard very little on the role of hirelings in Diablo 3 except that they are now called followers and that you can have more than one at a time.

---

What you've seen are the throw away helpers you can pick up on the field and they follow you, and are helpful, but usually die off pretty fast. They're not intended as a replacement for the mercenary system of yore.