It's the old debate of choice vs destiny
That is, free will vs determinism all over again. JKR's stance is pretty clear on it:
" Destiny is a name often given in retrospect to choices that had
And again from Dumbledore's mouth:
"It is our choices, Harry, that show what we truly are, far more than
our abilities" ~Harry Potter and the Chamber of Secrets
So, our choices matter, they have consequences. Voldemorts choices happened to bring his own downfall, he is the one responsible, not some foggy prophecy. He pushed Lily beyond her limits, and she made her ultimate sacrifice, creating Voldemort's enemy.
After all, if you choose to kill people chances are that they'll try to kill you back and eventually succeed (live by the sword, die by the sword, what goes around comes around, etc.)
Would Voldemort have lived forever and ever undefeated if he'd ignored the prophecy?
Of course not. Had he decided to leave the Potters alone, he wouldn't have made Harry his equal and his mortal enemy, but being a dark lord is a dangerous profession. Sooner or later he'd have pushed someone else hard enough and they'd have pushed back just as hard.
Voldemort's choices, that's what determined his fate. The names of the heroes aren't that important : Harry, Neville (whom Rowling called 'might-have-been') or another kid... Sooner or later Voldemort would have created a foe strong enough to bring him down.