That was quick!
Some of the Core rules have leaked by the looks of things:
https://imgur.com/a/yuLGn5n
Edit: and an additional set for some of the stuff missed https://imgur.com/a/fC0revP
Plenty to go through!
So models can only fight in base to base contact now, there's no second ranks fighting which is a very interesting change. Various 'nid gribblies had a rule ot allow them to fight from further back so perhaps this becomes a more readily available rule for units like Ork Boyz etc
I'm liking a lot of what we can see here, roll on the Indexes!