I love Psy, I was a fan even before Gangnam Style, and have been following K-pop for a few years now.
As for Gentleman, which I am totally obsessed with, I am skeptical if it will ever be as big in North America as Gangnam Style. It will definitely be #1 in South Korea for a very long time, I'm sure, but I don't know if Americans will embrace it the same way as before. We are really fickle when it comes to internet phenomenons....how many viral videos have a sequel that you know of?
Even so....I am happily doing the Abracadabra dance every time I hear it!