Nothing is "surely" about that, you're just stating your opinion, providing no real argument or supporting evidence whatsoever.
How about I provide some counterexamples:
* VHS vs. Betamax. Betamax considered superior by many, never took off.
* Facebook vs. Google+. Pretty much every tech person prefers Google+, but since Facebook is so established, nobody wants to leave it.
* Laserdisc vs. [whatever was available at the time]. Great format, never really successful.
Summary: I'm not concluding that it is impossible that bitcoin will be superseded by a newer cryptocurrency, but it's far from certain, and you made it sounds exactly like that.