Ironpants, Splashy Fish, Clumsy Fish and other Flappy Bird clones are on the top of the charts for free games in Google Play, and iOS App store. Clumsy Bird is currently the number 1 free game app in Google Play market beating Candy Crush Saga, and Unroll me.
With In-app purchases in Flappy Birds clones like custom characters, levels, better more targeted ads, and better graphics some Flappy Birds clones could be more successful than Flappy Birds.
Flappy Bird was a fun game for a while then it got boring. Its not really a game you could play long term and still continue to enjoy on a daily basis. So I'll pass on all the clones. 😛
I honestly do not understand how Flappy Bird got big to begin with, let alone its clones. Sure, it's a fun game to play when you're going to the bathroom, or stuck on a plane/bus/etc, but it really didn't seem to have any long term value to playing it.