If Cena is staying in the midcard and "I honestly don't think they see Cena at the top of the card any longer, and I think this midcard US title," does he beat Flair's world title record? Right now he has one less than Flair.
a) Right now he has about 6 or 7 less than Flair. 16 is only the kayfabed number that WWE history lists as official. Even then you get into the grey area of whether the big gold belt World title counts that same as the WWE title.
b) I would be willing to bet that no one in WWE really cares that much anyway. People online are about as worked up over this as they were for the possibility of Undertaker v. Sting, and it turned out that no one in the real world really wanted to run that match, either. If #16 ever happens, it won't be a big deal, I can almost guarantee.