"Like any team that only carries two quarterbacks at this time, you're rolling the dice. We understand that," first-year 49ers coach Jim Harbaugh said, adding there could be someone new in uniform soon. "I anticipate that there will be one (third quarterback) in the building, practice squad or other. ... There's nothing that precludes us from doing anything that we feel helps our football team. That goes for any position."
The team opens its first season under Harbaugh next Sunday against the defending NFC West champion Seattle Seahawks. San Francisco also placed tight end Nate Byham on injured reserve Saturday with a season-ending knee injury. Cornerback Phillip Adams, guard Tony Wragge and wideout Dominique Zeigler were among the others released.
"I'd love to come back," McCown, 32, told Comcast SportsNet Bay Area. "As for right now, I'm headed home to coach (high school football in North Carolina) and will continue to stay ready."
Harbaugh was vague about what went into the decision to cut McCown, whose best season came in 2004 when he started 13 games for the Cardinals and threw for 2,511 yards and 11 touchdowns with 10 interceptions.
"There was an effort to get our best 53 on the roster. Just decisions that we made," Harbaugh said.
The team worked out former NFL quarterback Daunte Culpepper last month before signing McCown to a one-year deal for the league minimum of $810,000.
So, for now, it's Smith -- the 2005 No. 1 overall draft pick out of Utah -- and Kaepernick.
"We feel confident in Colin," Harbaugh said of calling upon the rookie right away if needed.
"It is a noteworthy honor that Frank was elected captain on offense and Patrick was elected captain on defense," Harbaugh said.
In addition, Harbaugh said the competition for Gore's backup is still ongoing. Gore on Wednesday received a new three-year, $21 million contract extension that could keep him around through 2014. The deal includes $13.5 million guaranteed.
Zeigler and Adams both were limited by serious injuries in 2010, when the 49ers finished 6-10 and failed to reach the playoffs or have a winning season for the eighth straight year. Zeigler went on IR in late November with a torn ACL in his left knee, and Adams broke his left ankle in the second-to-last game at St. Louis.
The Associated Press contributed to this report.