I think the latest Facebook scandal is no more than a media spin.
lots of newspapers were hurt by Facebook dominance and politicians in allegedly democratic countries fears facebook increasing social power.
so no wonder all those parasites are jumping on the opportunity to punch the media giant when he shows vulnerability.

The majority of the people don't really care whether facebook or google are collecting and possessing their personal data.
They see the personally tailored ads on their Gmail inbox accounts but they are still using it because it's free and convenient.
They share tons of personal data and give ultimate access to free apps on their mobile phones without even a blink.
the public doesn't really care but when the media is making noise he wakes up for a short time, grumbles and falls asleep again.

facebook value decreased the same way shares always decrease in times of scandals.
I am sure they will go up again unless the regulator will impose new striker regulation that will hurt the revenue Facebook is making.

What should Facebook do?
the simple and the most proven effective action in these cases is to wait until the storm passes because the public is known for his short memory