Analyst Todd Mitchell, of Kaufman Bros. Equity Research, has told Gamesindustry.biz that he expects two new downloadable episodes to be released next year for GTA IV, with the next full GTA title expected in 2011:

"I would expect that there would be two more pieces of downloadable content for GTA IV, that's what has been indicated to me, although formats are unsure. It's been indicated to me to me that would be the case," said Mitchell.

"Our outlook includes expected strong sell-through of Bioshock 2, and the release of two 'AAA' titles, each from Rockstar (Red Dead Redemption and Agent) and 2K Games (Mafia II and TBD), reiterations of 2K Sports and 2K Play's annual line-ups, an expected GTA title for the PS2, expected strong sell-through of GTA: Chinatown Wars for the PSP, and new GTA DLC for the Xbox 360 and PS3. We now look for the release of GTA V in fiscal 2011..."

From our own point of view, Mitchell's claims seem unrealistic and do not cite any influencing factors aside from personal theories, so we would advise you to take his claims with a shovel of salt.