#3 The Club
While WWE hasn't shown much interest in reuniting Finn Balor with his former Bullet Club stablemates yet, there are signs this could be changing. Luke Gallows and Karl Anderson have been exhibiting babyface-like behaviour lately and could be paired with Finn Balor for a feud against The Shield.
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While on the surface this would make The Club vs The Shield rivalry a babyface stable vs babyface stable, WWE might not mind that. Remember The Shield will have Roman Reigns, so to a percentage of fans The Shield will be the heels in the angle.
WWE might consider placing greater emphasis on The Club considering the level of tension starting to brew between the company and non-WWE signed Bullet Club members, namely the Young Bucks. WWE could strengthen their intellectual property rights claim of the "2 Sweet" hand signal and other catch phrases used by the faction by having their own version of the faction on their programming.