But right now, it's nothing more than hope.
"I really think after all's said and done and everything is considered, I think they'll stay. I hope they'll stay," Hargis said during Oklahoma State's game against Kansas.
"It's a great school and great people and great rivalries. I think it would just be a real loss to the conference for them to leave."
Missouri was the lone Big 12 member to abstain from the league's votes this week to invite TCU as a new member and to give the money from their top two levels of televised games to the league for the next six years.
Hargis took over as the Big 12 board chairman on Tuesday after Missouri chancellor Brady Deaton resigned the post, wanting to avoid a potential conflict of interest because he was planning to explore the school's conference options.
The Big 12 acted two days later on negotiating to add TCU and moving toward solidifying the grant of television rights that would make it more difficult for schools to leave the conference.
"I think Missouri, just from conversations we've had for a long time, would be very pleased with what we've done," Hargis said.
"I think the obstacle to assigning rights is if you're looking around, you don't want to leave your TV rights back where you were."
Hargis said he hoped the Big 12's next move would be an announcement from Missouri that it intends to stay.
"Then we're at 10, a good solid 10," Hargis said, including TCU in that total. "Whether we go beyond that this year or later is going to be up to the board, and I'm not sure there's unanimity on the board on that subject."
Hargis, who sits on the Big 12's expansion committee, said he personally is in favor of the league getting back to 12 teams. His counterpart at Oklahoma, David Boren, has also supported moving back to 12 but others -- including Texas athletic director DeLoss Dodds -- have said 10 may be enough.
"On our expansion committee, we're considering a lot of schools. Obviously, we're not going to solicit schools without a good rationale. We have schools that are soliciting us, that have contacted us, and so we're considering all of them," Hargis said.
"And the criteria is we want a school with strong academics, with strong athletic programs. We don't want a school that will be dilutive of our revenues. And we'd like them to be in our footprint, just for the ease of travel for our student-athletes and our fans."
Hargis said that didn't necessarily mean any new members would have to be within an eight-hour drive - as most are now - but that they'd fit "in this culture, this Midwest culture that we have."
Nebraska and Colorado left the Big 12 this year, and Texas A&M plans to move to the Southeastern Conference next year.
TCU, located in Fort Worth, Texas, would be the first team added since the league's creation in 1996.
"It's just a really good fit. They are in our footprint, they have traditional rivalries, it's a very strong academic institution and it has great sports," Hargis said. "You put all that in the mix and it's hard to think of a reason not to do that.
"We're very optimistic that TCU will accept our invitation."