Back-publishing 1,000's of articles is impractical and risky (for other reasons).
Would be curious as to why.
Also, while the pages clearly have different designs, it isn't immediately clear which is "better" (or that this betterness is due to its being dynamic versus static).
Compare this NYTimes article:
http://www.nytimes.com/2012/05/15/technology/facebook-needs-...
to this one:
http://www.nytimes.com/2014/10/28/business/virginia-plans-to...
Everything pre-redesign was published in as a static. Back-publishing 1,000's of articles is impractical and risky (for other reasons).