No, Konohomaru has the potential to do it, because he has the required KB skills to do it (something that not even Minato or Kakashi had and supposedly beside those two - Konohamaru and Naruto - no one has). As long as he masters his element, he should be able to do it, especially since he has tons of more talent than Naruto (not to mention his lineage isn't anything weak as well).
If Kakashi can pull out a Chidori a few times a day, then that already means that most of the notable ninjas have enough chakra to make it as well (a little lol, but that's how it is ;P).
Naruto's Rasenshuriken is more like an Wind styled Odama Rasengan, rather than just a Resengan with wind manipulation. The first version after the element was added, was the same size as an normal rasengan (that's where Naruto tested his new version with Kakashi's normal one, thus injuring Hatake's hand).
The thing with Rasengan itself, it was never complete. Without a diversion actions like KB, 4th's jutsu, or others, it's almost impossible to hit a ninja (not counting normal people and the movies). The reason why F:RS is big, is for the same reason that Jiraya's Great Rasengan is, since it's bigger it can block incoming attacks and is easier to hit with, plus it packs more power.
The normal chakra itself, is a mixture of all elements chakra, although it will still tide to the one to which the user is more attuned to. Not to mention, that the only known people who could use all elemental ninjutsu are So6p and Nagato (well Madara can use at least 3: water, earth and fire, plus the sub-element: wood, but that's probably thanks to H-face boost).