My guess is the PAC and ACC (unhappily) stick together for this round and we dust off these lists around 2030, but just for fun:
Home Runs (that are never coming)
ND
FSU
Clemson
UNC
Miami
Oregon
Washington
I guess I can come up with scenarios where the bottom three don't have other options, but these schools are all no-brainers if they want in.
Definite Takes/Adds Value
VT - Would have the largest football stadium/attendance/fanbase/effective market (VA+DC) in the B12 if they joined. FB isn't good now, but they have a solid history and good ratings despite recent performance.
Louisville - Up and down in FB, but they have some pretty high highs, and are only behind FSU, Clemson, and Miami in ACC ratings. BB was a historic disaster this year, but historically they're a top 10-15 program. Built-in rivalry with Cincy.
Utah - I know, their fans are annoying, but unlike the other realistic PAC prospects they care about/are good at FB, and after all this their games vs BYU will be appointment TV.
Reasonable Adds/Netural-ish Value
Pitt - Poor man's Louisville. Nothing all that spectacular in FB/BB, but the rivalry with WVU is a plus.
NC State - Reminds me quite a bit of us actually, but more historical success and a bigger state.
ASU - Pretty decent FB history, and a huge enrollment and metro to draw from. Their recent trajectory doesn't inspire confidence though.
Arizona - Mediocre-to-bad FB mixed with pretty strong BB, and they're the second most popular school in a bigger state.
Virginia - Mediocre-to-bad FB mixed with pretty strong BB and they're the second most popular school in a bigger state. I know UVA gets all the B1G buzz, but if you take out academics and location I can't split them from AZ.
Colorado - I kind of like the idea of bringing the Buffs back, but their revenue sports have been struggling for a while now, and I don't think hitching wagons to Deion is going to end well.
GT - Would be a tier lower except for location. I know markets don't matter as much in a streaming world, and I know GT has a tiny share, but Atlanta is probably a top five college sports market, so let's take a flyer.
Stanford - Hard to rank. Probably a tier higher on value, but they're not at all aligned with what the B12 wants to be, and I don't see them coming.
Gonzaga? - I'm not big on the basketball-only schools idea. You lose stability if you add a bunch of schools with different priorities (see the Big East). But the Zags are enough of a unicorn that I'm at least lukewarm on them as a one-off if we expand that direction.
On the Fence
Duke - Also hard to rank. How do you weigh blue blood BB vs possibly the lowest FB potential of current P5 schools? A good question for the media partners, but I'm erring on the side of FB for now.
WSU - A school in a decent sized state with surprisingly strong FB ratings. I think they're underrated a bit, but geographically they're still on an island.
Syracuse - A less extreme version of Duke. I'm bearish on college FB ever becoming viable again in the Northeast.
Cal - For athletic purposes they're a poor man's Stanford.
Pass
OSU - Has WSU's drawbacks without the surprisingly high TV ratings.
BC - I don't see their FB reaching their previous heights again, and there's not much else there.
Wake - Decent in FB now, but historically not much to write home about, and a small fanbase.
UConn - Poor man's Duke. FB program is so bad and poorly supported it's disqualifying for me if it's an all-sports invite.
Memphis/Boise - I thought these were reasonable runners-up from the last round of expansion, but why reach now?
SDSU/etc. - See above, but with more drawbacks.