There is something to be said for companies doing one thing.
MySpace still exists. If MySpace (were still) part of a larger company, they probably would have been shuttered by now as irrelevant. As long as Facebook just has one thing, 'Facebook', it will also safely limp along long after it is the backwater of the internet, a place you can't believe still exists.
> There is something to be said for companies doing one thing.
The only real difference is instead of shuttering they pivot. The name sticks around but they still delete all your old stuff[1], so the effect is the same.
But social networking is the core of what Facebook does, and that includes the failed phone. G+ is pretty much irrelevant to Google's core businesses, which are search and advertising.
Facebook is Facebook's primary product; they're unlikely to close it down and reallocate engineers to other products until they've tried very hard to make it a success.
Have you missed the memo? Google+ is "Google's central identity" in the new Google. Shutting down Google+ would be akin to Facebook shutting down Facebook.
That's just marketing speak. Sure, G+ is about getting a real identity and other personal info to tie together with Google reading your emails, tracking you across the web, and tracking you via Android etc, but a Gmail sign-in would provide a "central identity" without G+. That's especially true for most Android users.
What makes Google any different in that respect? How are Facebook users any safer than G+ users?