I don't think there's a massive worry about a string of clones after this as it's very similar to a lot of games I've played before anyway. It's basically Flappy Bird with a different control scheme - you tap to change the direction you're moving in. It takes a lot of the player control out of FB and it feels a lot less satisfying with more reliance on luck than skill seemingly.
I had no real issue with Flappy Bird in the end, there are lots of things that are hugely popular but don't appeal to me. It was well-made, looked nice and had a great balance of difficulty and competition; it did what it was made to do very well. I'm just pretty disappointed in this one as it feels pretty derivative. Still, that's no indication that it won't be hugely successful after all and good luck to him.