From the interview, he alludes to a reason that the match didn't happen and says that it had somethign to do with them not being able to come an agreement on how to do it. Is he suggesting there that he wanted to beat Roman for the title? I could be way off, but that's kind of how that came accross to me.
In any case, the match could well happen at Wrestlemania 40. If they have the opportunity to do the match then they really should in my opinion. Seeing Roman beating The Rock at Wresltemania just makes sense in terms of the Bloodline storyline/saga.
Cody Rhodes will win that title and he will likely be the guy to beat Roman for it but I don't think it has to happen at Wrestlemania necessarily. It's a long shot, but is it possible that they could have Roman pull double duty at Wrestlemania? Have him beat The Rock on night 1 and then have him go against Cody on night 2? It would be a stretch given that Roman is essentially part time these days and rarely wrestles consecutive ppv's let alone consecutive nights. but, it's a possibility IMO.