Following the release of the publisher's annual financial results last week, Pachter said in a research note that GTA5 is likely to launch during the company's fiscal year ending March 2012.
"We fully expect the next instalment of Grand Theft Auto to be released by Q4:12 at the latest, as the company's contracts with the three employees most instrumental in the game's development (Les Benzies, Sam and Dan Houser) expire in January 2012," Pachter wrote.
"In our view, management would have been irresponsible to enter into a contract with the three without some type of milestone for delivery of the game prior to expiration.
"We are highly confident that a next version is well into its development, especially given that the prior version was ready on the Xbox 360 in August 2007, and its release was delayed until April 2008 only because of technical problems with the PS3 version (and a contractual obligation not to release on one platform before the other)", he added.
"We estimate that over 200 people work full-time on the game, and estimate that fewer than 30 were required to continue working on the prior version past August 2007.
"To their credit, Mr. Benzies and both Mr. Housers have a reputation for being workaholics, and for expecting the same from their employees. We find it unfathomable that work on the next Grand Theft Auto began any later than September 2007, so the game will have been under development for four years by the middle of Take-Two's FY:12.
"We understand that the team is using the same game engine (the Rockstar Advanced Game Engine, or RAGE), and although we expect the next game to be the biggest and deepest ever, we don't think it is likely that the team will take more than four years to deliver it."
When the as-yet-unannounced title does launch, Pachter expects it to take retail by storm and possibly become a record breaker.
"... The next GTA may become the best selling game of all time, selling over 20 million units," he said.
Back in May, Rockstar North posted seven job ads related to a new title which sounded very much like it could be the next chapter in the GTA universe.