#4. It might decline the credibility of Universal and Intercontinental Championship

Seth Rollins and Roman Reigns won their respective titles at SummerSlam. But a Shield reunion might affect their title reigns.
If Shield enters a feud, it will lead to Roman Reigns not defending his title weekly like he promised on Raw. Seth Rollins too might not defend his title on a weekly basis like he used to during his first Intercontinental title run. That made him the best champion in WWE.
R-Truth wanted to 'kill' former WWE writer. More details HERE
Not only it will affect their reigns, it will also decrease their credibility as a champion.
Edited by Shiven Sachdeva