I too would like to add that Funko Pops are butt fucking ugly and are showing up all over the damn place. Their bubble will burst eventually (if nothing else because the market is over saturated) but don't be surprised when something similar takes their place.
Last month I went to the local used bookstore. I say bookstore, but the place is pretty big and in addition to selling a fuckton of used books they also have loads of used games, DVDs, music (CD and vinyl), musical instruments, puzzles, board games, toys and other collectibles. Scattered around close to the registers where multiple collectible figures from before Funko Pops that were extremely similar to them. The only real difference is that their heads weren't completely rectangular and they didn't have those awful, black soulless eyes. I had completely forgotten about them until I saw them, and even now I already forget what their brands were called. There were at least two different ones before Funko showed up and really exploded in popularity.
Funko's will fail, and like their closely related predecessors, like Beanie Babies, like treasure trolls, like every other fad collectible before them, something else will take their place as the new fad collectible.