Now that it's the new year, there is more opportunity for DLC to be put in the game, specifically in Story Mode. I think Rockstar made some excellent leading characters in GTA V and I would like to see their stories expanded upon. The two deuteragonists, Lamar Davis and Dave Norton should have their own Story Mode DLC. 

1. Gangland Warfare (Lamar Davis DLC) 

This DLC (as the name says) would be about Lamar Davis and his experiences and story through South LS. It would bring back features from GTA: San Andreas such as the actual gang wars , which would play a much bigger role in this. There would be new vehicles, more specifically lowriders, that would appear in the DLC and you could complete gang attacks with friends. You could complete missions like Hood Safari and Lamar Down from from Lamar's perspective. The main story itself would be about Lamar trying to get Grove Street back from the Ballas and ultimately "conquering" the hood. This DLC would be available for all consoles due to it's relative simplicity.

2. That Government Boy (Dave Norton DLC)

This DLC would be about Dave Norton and his experiences on the opposite, white collar side of crime, the corrupt FIB. A DLC revolving around things in the main campaign like Mr K and the IAA toxin. The new vehicles in this DLC would be new police cruisers, helicopters and boats. The new weapons would be shotguns, snipers and heavy pistols. You would complete the Prologue and The Wrap Up as Dave Norton. The story itself would be about Dave meeting Michael in North Yankton and later having to deal with problems with the FIB. I think that this DLC could have the oppurtunity to bring back Liberty City in an updated form (new apartments, interiors) and weave it into the story of GTA V. 

These are just some thoughts on story mode DLC. I just wrote these ideas down for fun and if you have any ideas of your own or if you wnat to add to this, please do so!