Grand Theft Auto Online, the multiplayer component which will be free for all Grand Theft Auto 5 players, could support microtransactions. According to Redditor 1880, the store section of GTA 5 (which currently has nothing available yet) points to a file that allegedly references something called "Cash Cards."
The XML file (also copied to Pastebin), specifically mentions four separate Cash Cards that range in value from $100,000 to $1,250,000.
"Cash is king in this town. Solve your money problems and help get what you want across Los Santos and Blaine County with the purchase of cash packs for Grand Theft Auto Online," the description for each of the four Cash Cards reads. "All purchased cash is automatically deposited into your character’s bank account. Spend wisely, cash therapy is fleeting."
Rockstar has yet to formally announce any plans for microtransactions, but this certainly seems like it could be implemented following the launch of Grand Theft Auto Online. The multiplayer mode is expected to release on October 1st and will be free for anyone who has already purchased Grand Theft Auto 5.
How do you feel about the possibility of being able to purchase in-game money with real-life money?