Cena vs Orton is one of the few 'Dream Matches' left within WWE. It has been expected to happen since both guys debuted in 2002 (or around that time), but Orton's rollercoaster career has prevented it from happening.
It is clear as day that Orton is the top heel on Raw and has been since Edge was traded to SD!. He has deserved this title opportunity/run ever since Triple H squashed him during his first reign, when he was ON FIRE and had the potential to [one of] the top guy in WWE.
It has been reported that triple H has basically booked this feud, so he can get his shot, but unless WWE were going to book Cena/Lashley II, then this was the only possibility. Kennedy has been booked terribly since being drafted over to Raw (losing to Super Crazy/Jeff Hardy in single's and Cena in a tag match), even though he was a credible challenger upon his debut. King Booker will be fed to Triple H upon his return, so that takes him out of the running and Umaga is IC Camp (and they have already feuded), so Orton is the best choice. He is also producing his best stuff in the company in a very long time, generating great heel heat along the way.
I don't care about what anyone else says, but I am really looking forward to this feud and *hope* it is booked correctly. When Triple H is added to the mix, it has the potential to be [one of] the best feud Raw has seen.