Okay, so as of right now there is no story-line logic behind this happening. The WWE, however, look like they are planning to push Nakamura to the moon, and an exhibition match with Cena on one of the big four pay-per-views would be a huge step in the right direction.
In terms of setting this up, it wouldn’t even be that difficult. Cena has put an open challenge out in the WWE before and if he did it again, the fans would explode if Nakamura’s music hit.
A match between these two would be a definite match of the year contender and it would definitely put bums in seats. The WWE is struggling for ratings right now and this match absolutely screams money.