"Now we wait and see," Niemi's agent Bill Zito said.
Hawks general manager Stan Bowman said it wasn't a contentious meeting.
"Obviously, Antti is a successful player and important part of our team," Bowman said. "But there are no hard feelings.
"But when it comes down to the business side, you have to look at comparable players who he compares to statistically."
Within 48 hours of the decision, the Hawks can walk away and make Niemi an unrestricted free agent immediately, or can accept the decision, which mandates Niemi would play for that salary for one season. The Hawks can accept the decision and then trade Niemi.
"To be simplistic, it will be dependent on what the number is," Bowman said. "I'm not going to get into dollar amounts, but basically our cap situation is tight, that's probably well documented. Depending on where [the number] is, that will drive the boat.
"At this point, we're speculating, saying we've got plans and mapped out different strategies based on how it will go. We're confident we'll make it work for us and we'll have a good team on the ice in October."
Niemi was expected to seek at least $3 million, after making $827,000 last season as he led the Hawks to the Stanley Cup title.
Because of salary cap constraints, the Hawks were believed to be seeking a decision in the $2 million range.
The arbitrator has a 48-hour window to decide, but can request an extension.
Bowman said he has talked to other teams about "different options," in case the Hawks don't re-sign Niemi.
"We're planning for a lot of different scenarios," he said. "I wouldn't be doing my job if I weren't preparing for different outcomes."
Jesse Rogers covers the Blackhawks for ESPNChicago.com.