When Wizards announced the change to Pro tour Philly's format, from Extended to Modern. Many voiced hope that GP San Diego (also Extended) would also be changed to Modern. Today Wizards announced that Grand Prix San Diego would be Innistrad Sealed rather than Extended. When I asked Zvi Mowshowitz at Pro Tour Philly about changing GP San Diego to Modern he responded vehemently against it, noting that it would invalidate a lot of preparation by players and teams working for Worlds.
The change is reflected on Wizards' 2011 GP Schedule.
The announcement came via the following tweet from Head of R&D Aaron Forsythe's twitter account: