I don't know what if anything will become of Tumblr. Re. the OP's question of whether Wordpress acquiring Tumblr would result in Tumblr source going open, I don't see why it would. Wordpress has thoroughly reinvented itself away from being the open source alternative to Blogger, in exchange for being the voice whispering in everyone's ear "you don't have the luxury of not monetizing your hobbies." So gifts of code to the public domain are about the last thing I'm expecting. Probably just means a more slick and commercial (and slow and high bandwidth) Tumblr-like look and feel for Wordpress websites, probably under Wordpress branding, since Wordpress Developering is already quite the cottage industry. Maybe they're trying to add a dose of artistic temperament and countermainstream appeal to the Wordpress developer community and culture.
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