Sounded like they knew this was coming. Based on what was reported when Petite became a FA coach, coaches are normally kept on two year deals. With them adding an additional year, each year, so it's always kept at two years.
So they knew he didn't resign for the additional year last year (which some reports suggest that Petite left by not resigning as well, though those came with a conflicting report that LaFleur let her m go).
If Petite did decide to not resign, I wonder why he decided he wanted to leave.
I assume Mike Smith didn't like Petite leaving, and might not of liked him getting replaced.
Anyways, Mike Petite is now with the Vikings, so hopefully Mike Smith doesn't rejoin him. As Vikings seem to be putting together a great coaching staff, and will be running the same schemes as the Packers.
Vikings are expected to be running wide zone offense like the Rams, and Packers stole the Rams defensive scheme, but it was basically Vic Fangio scheme, and they got Vic Fangio's defensive coordinator from the Broncos.
It would be nice to bring Vic Fangio in as a consultant, but 49ers already tried, and sounds like Fangio is going to sit the season out, collect the check from the Broncos (as coaches contracts are guaranteed), and maybe spend time with family.