Favre, who tearfully announced his retirement as Packers quarterback after the 2007 season, has hinted in recent days of playing again -- either for Green bay or some other team.
The 38-year-old Favre asked the Packers to release him but the team announced it would not give up the rights to the longtime NFL star.
Favre needs permission from the Packers to play with another team.
"We have to go with what's real," Thompson told the Milwaukee Journal Sentinel Saturday.
"We don't know what the options are right now. We'll talk about it internally. It's all guess work. This is a very difficult spot we're in. It's a very volatile situation and we don't have all the answers yet."
Thompson said Aaron Rodgers is the team's starting quarterback now, but acknowledged that Favre's return to the roster is a possibility.
Favre led the Packers to the NFC championship game last season.