As of right now, there are plans in place to feature Seth Rollins vs. Dean Ambrose as one of the bigger matches at next month's WWE Battleground PPV. It is likely – although not confirmed – that the feud between the two will spill into the SummerSlam PPV as well.
This could change, but Roman Reigns is not expected to get involved with the Rollins angle, as he will likely be facing Triple H at this year's SummerSlam event in Los Angeles. The idea is that Ambrose blames Rollins for turning his back on The Shield, while Reigns just wants his revenge on the Authority in general. That said, it's obviously possible their paths will all cross at some point in the near future.