#3 Is John Cena close to retirement?

There was a very indicative line somewhere in the middle of Cena's promo when he told Roman Reigns straight up that he's only around still because Reigns couldn't take over from him yet.
Was there any truth to that?
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While Cena has transitioned into a bit part player of late, is he even sticking around only because Vince can't completely - forgive the pun - hand over the reins to Roman Reigns?
It would certainly explain why Cena was switched over onto Raw from SmackDown Live, in an attempt to hurriedly get Reigns over before he reportedly beats Brock Lesnar at WrestleMania 34 to rubberstamp his coronation.
But if that statement did stem from truth, how long does John Cena actually have left as an active competitor in the WWE?
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