The Big Ten is going to look at four schools. They are: Rutgers, Notre Dame, Pitt, and Mizzou. The Big Ten's choice order will be as follows: 1) ND, 2) Mizzou, 3) Pitt or Rutgers. My guess is will be either Pitt or Rutgers as ND isn't going and Mizzou will probably stay in the Big 12. If somehow another team gets into the mi, it will be UConn or West Virginia (would be higher on the list if their academics - which matters to the Big 10 - weren't awful). Syracuse is somewhere beyond all of those schools as they provide nothing in football, do not generate a media market, and are good in an area where the Big 10 doesn't need help (basketball).
If the Big East has an opening for a football team, they will likely look at the following schools. Memphis, Central Florida, and Temple. There really isn't any other real choice for them is they don't want to look to the Mountain West for another team. Actually, of that group, the choice is obvious. Memphis. Besides, one 8 win football season isn't going to atone for the hideous history of their football program, to say nothing of its' non-eistant fan base. Central Florida isn't there yet.
Look for Conference USA to take Louisiana Tech from the WAC. And then the Eastern US is stabilized.
In the West, the PAC-10 is making some noise about going to 12 teams. This will cause much more turmoil. While they may make noises about trying to pick off Colorado or Teas, they are really looking at the following schools. Boise State, Utah, New Meico, UNLV, Colorado State, Nevada, Fresno State, Hawai'i, and BYU. You can immediately drop Hawai'i (distance and doesn't raise the national profile of the conference), BYU (the PAC-10 schools won't have them in their conference - to say nothing of the students at those schools, and the PAC-10 schedules non-football games on Sundays - BYU won't play on Sunday). Utah is the obvious choice. For the second, I'd say they take Colorado State over Nevada.
The Mountain West would be down to 7 teams and would etend bids to Nevada and Boise State. This will cause trouble for the WAC, which will have lost Three schools (including Louisiana Tech to C-USA). Theres not many places they can go for more teams, unless they can make an argument to some Sun Belt schools that massive travel epenses is worth it to play with Hawai'i or San Jose State. Perhaps they can pick off North Teas (doubtful) or convince Idaho State to up to FCS D-1 (more likely).
Now if MIzzou decides to jump to the Big 10 instead of staying in the Big 12, then everything gets thrown in the air. But I don't think that scenario puts Temple anywhere but where they are now (MAC football A-10 basketball).
Bottom line: If the Big 10 epands, it shouldn't impact the A-10. And it will likely not really hurt anyone too badly. If the Pac-10 epands, it will probably mean very bad news for the Mountain West, BYU (who will be left there), and especially for the WAC (who will probably lose at least one, but perhaps as many as three of its best programs in just about any Pac-10 epansion scenario.