The thing is that Neville is not equal to Voldemort; Voldemort is half muggle born as is Harry. However, I reckon that Neville's character is being built up, which I'm glad about. To be honest, Neville won't be as great a wizard as Harry, and I'm not so sure that he would be a threat to Voldemort. Harry would be the only one strong enough to beat him. Remember Harry asking why Voldemort couldn't just wait to see who's stronger, well Harry is evidently the stronger.
However, Neville is coming into his own now. He's someone who Harry can properly trust more. He's trusting, loyal, and also brave. He would neer give up, and in that way he's probably like his parents. His character is developing, and he probably will continue to help out harry in the future. But he won't kill Voldemort, I don't think.