-there will be at least 2 more trailers before Christmas
-bikes are back, and operational
-planes are back, and operational
-weapons are customizable
-Grove Street will be in the game
-2012 release
-Microsoft will get timed exclusive DLC again
-parts of the countryside (mountains?) will be the border of one side of the map, while the ocean will be the border for another side.
-you WILL be able to play as more than one character
-parachutes are back (obv.)
-there are jokes about neckbeards and the internet generation in general
-phones/friends are back, but more in-depth and less annoying than IV's phone/friend system
-you can buy property
-you can buy cars
-gyms are back
-there will be another heist mission in the game (it may even be an activity you can plan when you're low on money)
-pedestrian interactions (random pedestrian/civilian events) are much MUCH deeper and various than IV's
-There will be AT LEAST one OFWGKTA song featured
-character customization is back, but it isn't as deep as SA's
-a character from the GTA III era will make an appearance in V in some way, shape, or form
-the injury mechanic has been revamped
-Bigfoot will be in the game in some way, shape, or form
-Marijuana plays a pretty significant role in the game
-there will be more than one way to save a car (other than keeping it in a parking space next to a safehouse)
-some cars will have retractable roofs