My thought is the content and the quality of the site will matter much more than the domain extension.
Quality of the content does matter. But, I believe the .COMs/.Nets/.ORGs/.INFOs will remain on the top. I meant to say, if .com is available, go for the .com domains and not for any other extensions.
True, these four will never be dethroned, but the question here is that how will Google start weighing the new extensions. As it's clear that these extensions are (more or less) niche related at all times, how will that affect ranking?
That may be true for the short term. But as the Internet continues to grow and these new domains become more accpeted, who knows what will happen.