The majority of what gets written never happens and when it does it never seems to happen in the immediate future. The narrative last year at this time was the Big 12 wouldn't be around much longer. Its a year later its still here. The narrative this summer is the Pac 12 is dead but its currently still standing. I see it being here next year. Who knows what will be talking about this time next year. I doubt it will be this. Any movement of Pac 12 teams to the Big 12 or vice versa probably won't happen until the next round of expansion which is probably years away. If the Big 12 has offered membership to certain Pac 12 teams I'm sure the offer will probably not have a time limit on it. I don't foresee the big 12 changing or having any other opportunities to add existing power 5 schools. I don't think any of the Pac 12 teams not on the invite list of the Sec or Big 10 will move until the Pac 12 gets so watered down that it isn't worth sticking around. Most of the conference have their media rights deals expire around the same time. Its also the period were expansion has been taking place. I think the Sec and Big 10 will set their next deal to expire around the time the Acc deal expires. I think the Acc will be the next to get poached. Which ever scenario plays out if any probably isn't in the near future.
I do not recall anyone of sound mind claiming the Big 12 dead after the defection of UT and OU. They were proclaiming that the Big 12 was clearly knocked down a peg and likely out of the "Power 5" grouping. That same thing holds true for the PAC 12 now that UCLA and USC are gone. The PAC 12 without those 2 teams is objectively out of the "power" conference discussion and into the 2nd tier if that is where the Big 12 has been banished to now that UT and OU are on the way out.
I agree that expansion is not likely to happen in a single year, but it seems to be at issue every 8-10 as seen by WVU's conference affiliations since the early 90's
Both Big 10 and SEC sit at 16 teams. ACC has the most potential raid candidates not only for value, but for geographic influence. ND is still on the table and likely to join a conference if the Big 10 and SEC get big enough and threaten to boycott them in scheduling. But if the best fish available between ND, UNC, and Clemson are poached by the Big 10 and SEC, additional members will be added to pad out the numbers and 20 per conference seems like the likely end point.
Hence for geographic dominance and to help the geographically isolated USC and UCLA, the Big 10 would at least consider adding more western programs. Likely Oregon, Stanford, Cal, and perhaps UW would be the most viable candidates. That leaves AZ, ASU, Colorado, Utah, Oregon State, and WSU, and possibly 2 of the former 4, all with the real possibility of desperately looking for landing spot in 10 years just as WVU was 10 years ago.
I'm sure some of those schools think they have a guaranteed invite to the Big 12 if the PAC 12 is raided and they are not the one's headed for the Big 10 or SEC. But that would be somewhat foolhardy as things can change and most of the remaining PAC 12, like the remaining Big 12, are not vastly disparate in value.
All that to say that the situation is volatile and there are lots of possibilities without a head and shoulders odds on favorite among them. The Big 12 should shoot for the moon and not just tell some PAC 12 schools that they have an invite if the PAC 12 is raided again, but try to leverage some of them to make a move when the contract is up in 2024. Even if some remaining PAC 12 teams are fairly confident they will be at the big boy table when the dust settles, they have to consider your point that the next raid won't be until after 2030. Could they survive as a viable big boy target if they spend 8+ years in a defunct conference without USC and UCLA and, the off chance that, 2-4 other programs bet on the jumping to the Big 12 in 2024? Does an ASU team gamble that a Big 12 spot will be better in the long run than hoping for the best in the current PAC 12?
It is obvious that college football is moving toward a Big 10/SEC as tier 1 and who makes the final cut is the focal point currently. But more schools are going to be left out rather than invited in and maintaining tier 2 status is the best outcome for most schools in the "Power 5". Some PAC 12 schools may make the cut into tier 1, some are legitimately looking at tier 2 as the best possible outcome and some will most likely be relegated to tier 3 like the AAC or Sun Belt. Which one's are which is the question and it's hard to tell what desperation to avoid being the odd men out will cause programs to do.