No way any of those schools would commit to Big 12 without being eliminated from Big 10 or SEC. Would be stupid of them to commit to Big 12 for 1/3rd of the money they would receive from other 2 conferences.
If they know they can't get in to Big 10 or SEC then they would consider. It's all about the money and the Big 12 is going to be way behind. Sucks bur it's the facts.
I gather you are talking about Oregon, Udub, Stanford and Cal, when you are saying that they will not commit, which is true if given time and a choice, all will choose the B10 or the SEC over the Big 12. So do not give them the time.
You go after CU, UU, and the Arizonia schools, they are not going to get invites to either the Big 10 or the SEC, and they have to be thinking that the moment any of the other four schools do, they are gone. So why be loyal to the Pac 12, and possible end up like Washington St and Oregon St. on the outside and getting into the MWC or go to the Big 12 where you are assured of staying in a P5 conference.
That forces the other 4 schools to decide, do I take the offer in hand from the Big 12, or do I wait for an offer from the B10 that may or may not be there? The B10 wants ND, along with UNC and UV more than they want Oregon and Udub. It's possible that Stanford and Cal are on the outside and then begging the Big 12 for a place at the table.
Or maybe, part of the deal to get ND would be the league also takes Stanford, a longtime rival, with great academics. The Big 12 after 2023 is back to 12 teams, while both the B10 and SEC will be at 16. Now is the time to take CU, UU, and the Arizonia schools and sink the Pac 12, and hope you can nab a bigger fish along the way.