Roth's plan would have been to stay on in Havana after Michael's assassination
So there would have been no private boat already waiting like Michael's private plane because Roth never thought “the rebels could win”

I doubt Fredo was even a consideration even if Fredo and Roth's alliance was known, “their priority sick Roth and getting out" of Havana

Michael's return from sunny Havana to snowy Tahoe, no wife no children greeting him was a telling scene However....
  • Kids do get tired of their toys so the little car [Michael's Christmas 'gift'!] was perhaps not quite abandoned It was perhaps too big to drive around indoors so left out for Anthony to play later
  • Kay knew Michael was back [in Vegas] but may not have known Michael was actually home in Tahoe, not heard him with the whirring of the sewing machine

Whilst I acknowledge the drama factor including “Was it a boy?” what was awkward for me, was Tom telling Michael such a personal, distressing, private matter of Kay having had a 'miscarriage' and losing the baby

Anyhow the sequence of events certainly put us in a melancholy mood! that -
  • Tom was telling Michael, the husband, Kay, his wife has had a 'miscarriage' instead of Kay telling Michael, herself
  • Michael's first question to Tom at the Desert Inn was “Kay know I am back?” but then Michael doesn't even greet Kay when Michael sees Kay at home in Tahoe knowing Kay has had a 'miscarriage'
  • Michael instead of comforting and talking to his wife, Kay [not dissimilar to Michael's talk! at Hotel Washington] who has just had a 'miscarriage' walks through heavy snow “to ask Mama if he could lose his family”
  • If Michael had talked to Kay instead of Mama or both Kay and Mama, perhaps their marriage might, just might...could have stood a chance of being saved

“The Big Three in Vegas” - Who was minding Michael's wife and his children, the future of the family, at Tahoe
No wonder Kay was able to have the abortion!