Marquez fractured his humerus in the season-opening Spanish Grand Prix in July and had to undergo a second operation after damaging a plate that was placed in his arm while opening a window ahead of the second race in Jerez.
The 27-year-old has not featured since and is now unlikely to return until the back end of the 2020 season.
A Honda Racing Corporation (HRC) statement read: "Marc Marquez will continue recovering in the coming weeks.
"The MotoGP™ world champion together with HRC, have consulted with and compared the opinions of a number of specialists in regard to the injury to the humerus of the right arm that Marc suffered on July 19 at the Spanish Grand Prix.
"As a result, all parties have decided to modify the planned recovery process.
"The objective of both Marquez and the Repsol Honda team is to return to the world championship when Marc's arm has fully recovered from the serious injury that occurred in Jerez.
"It is estimated it will take between two to three months before Marc can return to the RC213V.
"HRC has not set a grand prix for the return of the reigning world champion and will continue to report on the evolution of his recovery."
Repsol Honda team manager Alberto Puig said: "There has been a lot of talk about Marc's recovery and the various deadlines, but from the first day after the second operation we have said that the only objective that exists is for him to be 100 percent.
"We do not want to rush. Once Marc is in a position to return and compete at the level he knows, then we will think about the next objective."
Fabio Quartararo went into this weekend's Styrian Grand Prix with a nine-point lead over Andrea Dovizioso in the riders' standings.