Your last two sentences don't pass the smell test.

There's even graceful degradation in your set of solutions:

1. You drop FB. Now you just look on your spouse's Facebook when necessary, and your family learns to tell your spouse to show you stuff on FB. Annoying? Yes. Unworkable? No.

2. Your entire immediate family drops Facebook. At least one (if not all of you) can still communicate with the rest over text. And the rest of your family knows how to send a photo over text on an Iphone. Annoying to extended fam? Maybe. Unworkable? Definitely not. (In fact, I'd be willing to bet that it cuts out extended family spam and makes those moments of connection more meaningful.)

3. You attempt a quixotic adventure to switching your entire extended family over to some half-baked decentralized alternative to Facebook that will be usable in forever minus a day. Impossible? Yes. So choose #1 or #2 above.