I've always found the magazine vs typical blog format to a bit of a false dichotomy - it is entirely possible to create a site which has content segregated between both magazine style feature articles and smaller blog posts.

As for incentivisng the 'A-listers' to contribute, the quality of the content is more important than the person delivering it. A project like this has the potential to offer a great platform to newcomers - although it would require a strong editorial process.

Obviously there's a lot of kinks and details which would have to be developed, but I think it's a good idea - nothing ventured, nothing gained.