Sounds fishy just because one thing: Undertaker was suppose to win it at Rumble vs AJ, then do Chamber and lost, then do Wrestlemania with Cena. With all due respect to Taker, either those matches would be pretty short or he would broke in half during Chamber bout and be in wheelchair at Wrestlemania.
First thing that came out sounds way more plausible and that is that Cena wanted Nikki Wrestlemania moment so they did proposal thing. Otherwise would be crazy stupid to sideline Cena at the biggest stage of them all when you could have him in either with Undertaker as main event or in title match. Vince knew that, Dunn knew that, Cena knew that.
But also can't get who would've got AJ Styles at Wrestlemania.
According to that report, Orton would. Orton winning Rumble was always the plan. They would do Wyatt/Orton thing at Chamber and then Orton would get AJ at Wrestlemania. And yes, that would be great match and if that was the plan, shame it was changed.