We all know that Grand Theft Auto V is going to have multiplayer. Like it or not, just about every game has some facet of online interaction these days. GTA IV had a ton of modes that were a whole lot of fun and in GTA V we should look for Rockstar to take what they already had and expand upon it.
Free Mode
You have to expect that GTA V will have a Free Mode like IV did. This mode will let you fully explore the massive GTA V map at you leisure, dodging other players as you go. There will undoubtedly be an option to turn off friendly fire so players can't hurt each other, but that's not a lot of fun, is it? Sure, Free Mode was always full of trolls and griefers, but sticking it to them was a blast.

As you probably already know, the GTA V map will be unprecedented in its sheer size, so it will be interesting to see how Rockstar makes it work, but work it they undoubtedly shall. With the larger map, it would also be nice to see more players in the lobby. So you don't have to travel as far to kill them, of course.
Racing
Racing has ever been a part of Grand Theft Auto in the pure sense, however that said that there is a whole lot of cool cars to steal and drive as fast as you can! In GTA IV, there were a lot of variations on the racing theme that made it fun for people who weren't even into racing games.
For one, there is the weapons. If you like racing and also being able to blast the guy in front of you with an Uzi, GTA will have you covered. This mode – which was simply called "GTA Race" previously – will be in GTA 5. Once again you'll probably have the option of simply hopping out of your car and taking pot shots at the racers on the side of the road. Sure you'll finish last, but you may end up with the most money in the end by simply taking out all the other players several times.