couple things i want out of it:
* car and bike mods
* the ability to buy every single building
* more freedom (GTA4 was billed for this but only gave you two choices between good and bad that made no difference to the story)
* more crazy shit, RC vehicles, jet packs, funny radio stations, random violence, tanks, jet fighters, gun boats etc
* ability to grow and expand your "family", "posse", "group of russian immigrants" into a major crime family with the ability to take out the competition.