highly doubt bitcoin will fizzle out at this point, cryptocurrency and the fundamental technology its based upon will stick around forever.
even when the speculative bubble bursts, and even if bitcoin goes back to being worth $0.20, it'll still be used, as it was for years before this current craze, for secure and anonymous online purchases. it was good for that. totally untraceable, after all.
what could seriously damage it is if world governments get together to try and stamp it out. well, good luck. there's about 150 meme coin currencies at this point. and it doesn't really look like that's happening; it rather looks as if the major financial players and institutions are starting to soften on cryptocurrency, now they see its investment potential (or the ability to turn a quick buck).
if they can get some sort of regulation and take all the power away from some pretty shady exchanges/private individuals, it could become a semi-respectable thing.