Southwest, which is truly a US trunk carrier now, would do well to try code-share agreements with select smaller carriers, instead of 'going it alone'.
Perhaps, but not in one that is a hub (even if they don't want to call it that) they are competing in and want to further their presence at. Something down in the SE perhaps. Anyway they have made some small steps in that direction as of late with some of the agreements they have signed with other airlines.