On the subject of your last sentence, I think it's pretty sad that yoko being there probably caused a lot to be left unsaid. I think if they could've had any time in a room together to just talk and not trudge through production, they might've been able to be real with each other and at least salvage their relationships. Maybe even ironed out some issues and entered a new phase as a band.

It would've at least been cool to see them collaborate for songs on their solo albums. But we as fans will never know what all the issues were and if they could've ever worked through it. But I kind of think they all thought they would get back together in some way until John got assassinated

The Beatles broke up because of egos mostly. They were all basically doing their own things towards the end anyway and Abby Road and The White Album are basically solo songs from each member just mashed together. I also believe both Paul and Johns first solo records were full of songs meant for the last two Beatles albums.