"It doesn't mean anything," Katz said of his resignation. "There are a lot of different ways for me to engage in public policy and the debate in Philadelphia."
Asked if he would rule out a run, Katz said, "I have choices."
Katz, a former municipal-finance consultant, recently has been spending most of his time on his historical documentary series, "Philadelphia: The Great Experiment," a project that he says is expanding.
That commitment, paired with PICA's recent appointment of a third executive director in Katz's three years as chairman, drove his decision, he said.
"I'm so busy with what I'm doing with these films and I need to be fundraising for the projects I'm working on," he said. "I just felt this was a good time to go, an appropriate time."
Katz first ran for mayor in 1991, when he lost the GOP nomination to former Mayor Frank Rizzo, who died the summer before the general election. Katz won the nomination in 1999 and 2003, losing both times to Democrat John Street.
Under Katz's leadership, PICA several times forced Mayor Nutter's administration to revise its five-year financial plan, which the board must approve every year for the city to continue receiving state support.
PICA never rejected the plan, but it came close in 2012, when board member Sam Hopkins voted against it and Katz publicly flirted with joining him. (It only takes two of PICA's five members to defeat a five-year plan.)
PICA, created during the early 1990s fiscal crisis, will expire in 2023, when city wage-tax bonds it supports are paid off.
Katz hopes state and city leaders will find a way to make it permanent, saying its five-year budgeting approach has been good for Philadelphia.
PICA's new executive director is Harvey Rice, former chief of staff to City Controller Alan Butkovitz.
The other four board members are appointed by legislative leaders from both parties in Harrisburg.
On Twitter: @SeanWalshDN