Their silence is now louder with all 3 of the other 4 Corners teams pretty unambiguously stating they don't plan to leave.

Also I think it's worth noting that the Arizona president said that if the Big 12 can get Arizona and Colorado, then it would destroy the PAC and start a chain reaction.

Of course he's going to talk about his, but worth noting he also selected Colorado as the other one. Wouldn't surprise me if Colorado has reached out to a few teams seeing if they'd leave to the Big 12 with them.

Finally the idea that the PAC is considering Colorado St seems to point to Colorado potentially debating leaving

The best explanations for considering CSU would be either

1) replacing the Colorado market after losing Colorado

OR

2) using CSU as an implicit threat to keep Colorado from leaving - "well if you leave then we'd potentially go and elevate your in-state competition to P5...would really be unfortunate for you, wouldn't it"

Both of those only make sense if Colorado is legitimately considering it