Personally, I am hoping that we'll get a version of BT2 where:
* You *don't* become completely invincible for a big portion of the game. (It isn't much fun when enemies can't hit you with physical attacks or spells; this becomes an issue in at least the DOS and Apple 2gs versions.)
* Your attacks have at least a reasonable chance of hitting for the entire game. (In at least the Commodore 64 version, there comes a point where your physical attacks stop hitting entirely without magical aid. Also, the C64 version has a bug which makes special party members that are supposed to cast spells or use breath attacks (including the Wind Dragon and Wind Mage illusions) useless.)

(There's also some things I would like to see in BT3, including a few cosmetic things (it would be really neat to hear double reed renditions of the bard songs, especially since there exists a Galvanic Oboe (which counds like a flute in the C64 version)).)

It is here:
https://www.youtube.com/watch?v=Tcp_5hfomF8&feature=youtu.be

Will GOG be getting this update on 10/23 at 2pm PST?

I sure hope so, but GOG updates are notoriously flaky. Hopefully things happen fast this time, but you never know.

One little observation from the trailer:

On becoming an Archmage, the spell Rimefang was learned. In original BT2, this spell did not exist. In BT3, this spell did exist, but as a 7th level Sorcerer spell; it did twice as much damage as Mind Blade, but differed in that it was frost rather than shock damage. (BT3 introduced elemental properties; some enemies take half or double damage from certain spells and breath attacks. For example, the Flame Horn works well on most of the enemies in Gelidia, but Rimefang isn't that great there.)

Destiny Knight ???