A few of quick thoughts about this before I miss my bus:
1. I'm in favour of leaving for a week at first, if only to send a message.
2. Eventually, we'll all need to move. For-profit social media platforms are pretty much guaranteed to introduce biases that affect your social connections. This is not a good thing.
3. OTOH, I'll always have some level of Twitter presence. Too much of the professional marketing is necessary, there. Personal sphere, though. That's mine.
4. It will take time to build up the next platform, but that cycle is much quicker now than it was previously. The first thing we did when we joined Twitter was find other WGBers (and other friends, for those that have some). As we move from platform to platform, the first thing we do is find and connect with those we're already connected to on the previous platforms.
5. On the news junky thing, I (and some of my archaeo-nerd friends) have gone back to RSS feeds this year. The quality and volume of news is so much better than it had been when I relied on SM to provide it.