Personally, I am fresh enough to all this that I feel it's prudent to kind of sit back on the discussion, and am leaning toward the "defederate" option.
However - I deleted my Facebook years ago, and never had Instagram or Twitter. It would be nice to interact with my own family and friends who do most of their online presence in places like that. So I kinda get it. I'm not after the mass-produced content but it would be cool to hear from people I know again that I've lost touch with because I'm stubborn about FB.
Just spitballing - and please consider that I haven't been at Lemmy long enough to know if this is a terrible idea - but what about an instance that hasn't blocked Facebook and other big corpos, but doesn't raise their content by default? Like what if you have to actively connect with people on them? Seems like a decent middle ground, until Facebook decides to break it anyway.