#4 Seth Rollins begins a feud with Shinsuke Nakamura
If he remains a heel, Seth Rollins could start a feud against quite a few Superstars on SmackDown. One of the more interesting options is Shinsuke Nakamura. It would be a fresh match, even though it happened at Survivor Series 2018 in a Champion vs. Champion bout.
However, there are still many things that make a current day rivalry between Rollins and Nakamura fresh. The roles would be reversed, with The Messiah excelling as a heel and The King of Strong Style doing much better as a babyface.
Also, Seth Rollins wouldn't be distracted by another feud happening simultaneously, like he was with Dean Ambrose at the time. If a match with Shinsuke Nakamura is his sole focus, you better believe it will be great. The two could have a series of great matches on TV and possibly, pay-per-view.
Seth Rollins and Shinsuke Nakamura's styles mesh so well together that it would be a shame if they didn't get to showcase it with no outside distractions. Now is a perfect time, with Nakamura heating up once again as a face and Rollins seemingly remaining a heel upon his return to WWE.