It's been well-documented for a while now that WWE has high hopes for Roman Reigns and are grooming him to be the next top babyface star of the company who will hopefully take over John Cena's spot eventually. As of right now, they are still planning on making 2015 the year that Roman Reigns truly breaks out as a main event Superstar. It's very likely that Reigns will end up winning the 2015 Royal Rumble Match and go on to capture the WWE World Heavyweight Championship at WrestleMania 31, most likely from Brock Lesnar.
However, there are people backstage that are worried that Reigns might not be quite ready for such a massive push. It's no secret that he still needs to do some work on his promos and he's also not as good as he could be in singles matches yet. But WWE officials are adamant that the time is now to create a new top Superstar and Roman Reigns is their choice.
As for Roman's former Shield brethren Dean Ambrose, WWE officials are still high on him as well and both Ambrose and Reigns have proven to be fairly strong merchandise sellers for the company. The general feeling backstage is that Ambrose is a better overall performer than Reigns at this point, both on the microphone and in the ring. However, it comes down to what the company looks for when they're trying to find the next top Superstar like a John Cena, and Dean Ambrose, much like Daniel Bryan, simply doesn't fit the mold of what they're looking for as much as Roman Reigns does.
Moving forward, WWE will continue to push Reigns as the next top babyface to eventually take over for John Cena.