Florsheim, who has been appointed the chief executive of the home emergency services company Homeserve, is leaving Sky after 12 years.
The pitches have now been postponed until 23 November, when WCRS and Grey will take part in a final shoot-out for the business.
Following Florsheim's exit, Sky has handed marketing responsibilities to its communications director, Matthew Anderson. Anderson joined the broadcaster from Ogilvy PR in November 2005.
The expansion of his remit to include marketing responsibilities is likely to fuel speculation that Sky will opt for the WPP-engineered "Team Sky" option in favour of Grey.
Florsheim and the Sky brand marketing and sales director, Charles Ponsonby, were understood to favour an open pitch, while Sky's chief executive, James Murdoch, was said to prefer the WPP option.
Murdoch said: "Jon has played a significant role in the growth of Sky's customer base and the strength of its brand.
"He is a valued colleague and I would like to thank him personally for the fundamental contribution he has made to Sky's success."
The pitch follows Sky's decision to part company with WPP's United London, the incumbent on the business.
Florsheim's exit is one of a number of executive changes at Sky. Mike Darcey has been promoted to chief operating officer from group commercial and strategy director, while Brian Sullivan, the former director of product strategy and management, has been appointed to fill the role of managing director of the Sky customer group.