All we really know is multiple people die, and at least some of them are hotel guests. It'd be pretty nuts of them to kill off Tanya - only because she's such a great character and the link between the two seasons thus far, but who knows?

The running theory on the subreddit is that Greg is the "cowboy" that the older brit mentioned as the person who he'd do anything for but who is also straight - that he hired those guys to kill Tanya so he'd get her insurance money - but that seems semi-far fetched. Still - they're clearly conmen - between the "nephew", the "Is that the Queen of Sicily?", Gore Vidal being a friend (he died like 10 years ago?), etc - there's a lot of signs there that they're simply trying to con a rich old naive lady.

I think your theory of Bert hitting his head a bunch is something so obvious but I didn't even think about. If that's the case - it's very White Lotus of them to have Albie run off with Lucia only for us all to be like, "Yeeaaaaah that shit's gonna fail and the cycle will repeat".