3 Reasons the Shield should split up again, and 3 they should not.

Should split up: The days of stable warfare are over

The Four Horsemen effectively killed the stable warfare concept in pro wrestling, and the NWO eulogized it.

There's not much more to be done with dominant stable factions. Stables work much better with mid-card talent who need the boost in popularity. Given that Reigns, Ambrose, and Rollins are all former world champions, they don't need the Shield stable to get over anymore.