One of the primary concerns, and it's a good one, of SEC expansion opponents is in regards to how additional teams will mess with traditional rivalries. To that end, I would ask you how much time is required to make a tradition.
It's easy to forget after 20 years of divisional play, or not be aware if you're under 30, that the SEC schedule hasn't always been neat and tidy. Certain rivalries do go way back (Alabama-Tennessee, the Egg Bowl, etc.), but some schools almost never played each other.
Consider Tennessee, Florida and Georgia. For the most part they have ruled the East since 1992, ensuring that there are heated series between them. The latter two have a genuine rivalry extending back almost 100 years. However, those two played Tennessee a combined 26 times (Florida 16, Georgia 10) between the SEC's first season in 1933 to 1991. It's hard to think about a time when Tennessee didn't have a series with those two, but that was the norm before we had divisions.
There are plenty of other series like that within the divisions now. Between 1933-91, Ole Miss played Alabama just 20 times and Auburn just 14 times. LSU and Auburn played only 17 times. Vandy played Alabama more than twice as often (56 times) as it played Florida (25 times). Kentucky played its current designated "rival" Mississippi State just 15 times.
What feels like the norm now is anything but when you look at the history of the conference. After the jump is a table showing all of the SEC series among the original ten members. The first column of numbers displays the percentage of the time that the series was played before the 1992 expansion season (and is sorted in descending order of that). The second column of numbers shows the percentage of the time it was played after expansion, with the final column showing the difference between the two.
The SEC has already shaken up its series frequency quite a bit, and it got stronger as a result. That's no guarantee that a 14-team SEC will manage the transition as gracefully, but it has been done before.
The team names are listed alphabetically in each cell, so don't worry about who should be listed first and all that. Also, keep in mind that the Alabama-Auburn series was suspended between 1907-48 due to disputes between the programs.