While a great idea the problem of course is there isn’t a ready replacement for what Facebook provides. Where would families migrate to for communication/collaboration/community? The closest free alternative is of course Instagram, owned by Facebook. Who can build a privacy oriented alternative that charges and also gains a sufficient network effect?
For families? Our uses a mixture of e-mail, text/iMessage, iCloud photos and Dropbox
Facebook has discussion forums, rich messaging, groups and events, classifieds, image and video editing/enhancement, and many more features all bundled into one platform. You'd probably need 15 other websites and services to replace it.
If we just had truly protective privacy laws and standards we could just use Facebook and enjoy what it is capable of doing without guilt.