The BigG1 payout and prestige is higher, as is their academic and playoff profile. Even with the LHN payout I’d see it being appealing to Texas.
If Texas stays the Big12 will undoubtedly try and poach some PAC teams. Whether any would go I don’t know, but there’s several PAC teams who aren’t happy with their payout, tv situation, or Larry Scott’s leadership.
The Big12 has already all but said that G5 teams and byu don’t interest them in expansion. UCF could be the one exception, if they expand with a non P5 team, but I doubt it since they are greedy and don’t want to split the tv money unless it’s a big profile P5 team like USC.