*Horde Leader randomly returns after a long absence*
It's good to see some people understand that the "Ghirahim is Zant, Midna, etc." from the Brawl era is a fallacious argument because it assumes a circumstance that simply does not exist now. As a person who used to debate Ghirahim around these parts, that was thrown into my face repeatedly. I think also from a popularity perspective he might be a bit more elevated than Zant, Midna, etc. was back then (speculation on my part).
In addition, the "one-shot" argument, regardless of refutation, sounds pretty weak to me at times when people are simply sheepish about his inclusion purely on those grounds. In the minds of many that is the one hurdle they envision, and honestly if that is all in his way than I think its a testament to the character if the quantity of his appearances is the thing called into question and nothing else.
That whole line of thinking could be discarded if he were to make an appearance in the new 3DS Zelda game.
Although his fabulousness would be undermined because of the medium. I'd be more interested in a Skyward Sword prequel involving him and master Demise's initial reign on the Wii U than that, and more than a game involving you wielding Ghirahim (although the idea of him being your "Navi" sounds like a good time ha).