This has too much potential to go wrong. Most people will, at best, stick to three households at a time, rather than a closed circuit of 3 bubbles... and it sounds absolutely impossible to police.
We only have one set of parents, so it's okay for us theoretically... they're desperate to see DH. But they'll also want to see the wider family - his mum has two siblings and typically sees them often, and his dad has one sibling who is by themselves... it doesn't even work with a small family.
We were planned to spend the day together and see no-one, but his parents are pretty upset about it. They're struggling with not being able to see us, so if it's allowed, there will be pressure to go and see them.
Selfishly I'd rather the rules stayed as they are and we weren't in lockdown for so long. I miss seeing my close friends, the in-laws are lovely and I miss them too, but I'd live with video calls and a weird Christmas to be able to spend a more normal year with them next year.