I dont see the SEC adding just one team. If they are going to expand they will add one on each side, and there have been no rumors of any kind that have lead me to think there is someone in the East coming on board.
A&M is going to happen someday. And I believe the SEC will also add OU and Okie St.
SEC Additions:
A&M
OU
Okie St
Texas Tech
BigTen:
Mizzery
Iowa St
Kansas
K-State
Pac10
Texas
BYU
Baylor replaces BYU in Mountain West
Of course, this is all just guesswork. But of all of the rumors I have heard, these make the most sense.