You get dangerous when the Dems pull within 2 or 3 of control. Defections are bound to occur...or at least overtures. If the Senate remains as polarized as it is now, I could see severe infighting in the majority.
Rubbish. Senators don't switch to be in a minority Party. No Senator wants to lose *both* seniority as well as Majority status. Goodbye chairing committees. Goodbye getting your pet legislation introduced on the floor, much less passed. Goodbye campaign funding. Goodbye prime Senate office space. Goodbye top-level staff funding. In short, goodbye.