IMO it is wrong to assume that the SEC is done with big moves. Clemson & FL State would be huge gets if they can get out of their GOR. I am sure they are waiting to see what happens with UT/OU path out of Big12 and it's GOR.
Also, I seriously doubt USC is just standing on the sidelines waiting on the Big10. Why wouldn't USC be in play for the SEC? If there was potential for OU/UT to join the Pac12 a decade ago. Seems like a really bold move for the SEC would be to add USC, UCLA, Arizona & Arizona State. An SEC "really West" division would be very attractive:
Texas
Texas A&M
Oklahoma
Arkansas
Arizona
Arizona State
USC
UCLA
drop UCLA and Arizona and it would still be attractive. But if the SEC has a chance at Clemson & Florida State- then the above 8 makes a nice division or part of 4 six team divisions.
Why would the SEC want the Arizona schools? In terms of attendance, viewership and overall interest they are not good. They are a hell of a lot closer to Vandy in that regard than the top of the SEC. UCLA isn't a whole lot better. Start throwing out most of UCLA's rival games, combine that with getting their ass kicked every week and while it's hard for people to care less about UCLA football, that's one way to make that happen.
USC would be attractive to every conference. The Arizona schools aren't.