First off, Randy Orton will beat John Cena. John Cena's match at Mania is always important, because it's John Cena. Orton needs the belt to be important, so I think he holds onto it for this match. Also, I think Cena does something with Hogan involved at Mania.
Next, Lesnar is beating The Big Show. No doubt about it.
I'm actually going to pick Bray Wyatt over Daniel Bryan. They clearly want to elevate Wyatt, and this seems like the best way to do it.
Cody Rhodes and Goldust will beat the New Age Outlaws. At least, I really hope they do. They were the team that was good enough to beat the unbeatable tag team, The Shield, so they probably shouldn't lose to two retired guys who are well past their best days.
There will be a surprise appearance from an NXT Superstar. That person will be Sami Zayn. Most of the WWE Universe will have no response. I will start cheering from my house. He will eliminate my favorite wrestler, Antonio Cesaro. They will begin a feud against each other. Everyone will watch these two wrestle and have the wonderful moment of, "Holy shit, these guys are awesome." An angel will get its wings.
Chris Jericho will be a surprise entrant, because why not. And no, I'm not going to take the time to look up Fozzy's tour schedule to see if that is even possible.
Sheamus will come back for the Rumble. He's been out for a really long time, so this seems like a good time for him to come back.
Dolph Ziggler comes back for the Rumble. At least I hope so, because that will mean that he no longer has any ill effects from his concussion.
Finally, Daniel Bryan will win the Royal Rumble. Yeah, I have him losing his singles match, but that makes it the ultimate emotional rollercoaster for Bryan supporters. And who is a better guy to face Orton at Mania? Batista? That's boring, and Mania is all about mainstream publicity. Daniel Bryan is the kind of feel good story that they can put on the national media. They can point to his famous yes chants that have taken over at sporting events. Daniel Bryan is finally done being the underdog, as he's on his way to being the big dog of the WWE.