Can I just confirm, to save me the agro of delving deeper, these are basically renamed side chains?
I remember when it was a theoretical. The tech didn't exist. Same as Lightning.
I'm not entirely against the notion of side chains, since BTC is permisionless it's up to people what they build, but I have two main reservations;
1) The only solution seems to be to change Bitcoins underlying code. Not a deal breaker in and of itself, except 2)
2) The people pushing this will quickly move on the the next "must have" change. I can tell, by their zeal. Zealots don't ever chill. It's not in their nature. I don't like that when there's so much at stake.
Slowly does it.