When Microsoft [henceforth MS] announced the acquisition of LinkedIn [henceforth LI], at first I thought - why in the world? But after looking at both the [large] number of users LI has and also the quality of LI’s users [all grown-up professionals], I now feel that LI is one of those very few social networks in the world that have the real potential to become serious Facebook rivals, provided these networks morph into full-blown social networking platforms [others include Skype and Twitter]. It's my genuine fear that FB might become insurmountable soon if a strong rival to it doesn't emerge soon - and existing networks with hundreds of millions of users have the best chance of rivaling FB. New networks simply don't stand a chance due to network effect.
That being said, LI shouldn’t alter/adulterate the core ideology behind LI by adding FB-like features directly to the core LI service. Such a step would corrupt LI's value proposition - the very proposition that makes people have and use both FB and LI rather than shifting to FB alone. Instead, a separate service that relies on LI credentials/identity can be launched which allows these professionals to have fun with photos, videos, animations, games, etc., without disclosing their real LI profile.