If we were talking about Japanese MMA and Japanese professional wrestling, then there might be a combination, though it's doubtful, since the two are so similar (and have many of the same characters).
The fact is, though, if we're going to have this conversation in the context of the United States, then McMahon is an idiot. Periodically, I watch an episode of RAW or Smackdown, and I've got to say that there are two things that strike me about professional wrestling today.
The first is that they're not even really trying to put out a quality product anymore. The storylines are boring and the characters that are being introduced (for lack of a better word) suck.
If we were comparing the characters from the WWE to the fighters in MMA, I've got to say that the characters in MMA are more interesting, which is shocking, because the characters in MMA are bound to reality, and the characters in the WWE are not.
The second is that MMA produces a more exciting product constantly, not because it's real (though that's certainly one of the reasons I enjoy MMA more), but because the believability of professional wrestling has deteriorated to the point of non-existence.
Oh, and let's not forget that professional wrestling has attempted (badly) to adopt MMA moves to appear more realistic. See The Undertaker, and the world's stupidest gogoplata.
There's a reason that former professional wrestlers are coming over to MMA, instead of the other way around (which is how it used to be).
I had a trickle of yellow liquid run down my trouser leg when I saw this, since when did the undertaker go from carrying an urn and tombstoning people to being trained in bjj (bad ju-jitsu),lol one positive rep coming your way for noticing sir.