I’m reasonably sure that in his ego-maniacal mind he’s a real candidate, but then so was Ralph Nader. The difference is that the Republican party and its propaganda wing and the are treating Trump like he’s a serious candidate. The reason they’re doing that is because he’s their stalking horse. He’s there to make the other crazies look sane by comparison. Next to Trump, Sarah Palin, Ron Paul, or Mike Huckabee look like frickin Adalai Stevenson.
About halfway through the primaries, once they’re ready to anoint a front-runner, you’ll stop hearing anything about Donald Trump whether he pulls out of the race or not. If he’s gotten any traction in the early primaries, look for a more extreme candidate from the Republicans. If he falls flat, look for someone who appears to be more mainstream. His results will help them gauge the mood of their base, and his wackiness will legitimize the other wackos. That’s how The Donald fits into their plans.