1) 4 or 5 movies between 1970 and 1980
They would have produced movies. Ringo would've been in more movies, George would've still been involved w/ Monty Python, John and Yoko would've probably gotten into more multimedia projects. Paul is the only one who consistantly toured. George did one or two, Ringo didn't until the mid-80s on, and John did a handful of live shows. When he was working on "Double Fantasy" he discussed touring but it would've been theater-sized venues and with Yoko.
2) "The End" would've never been written
Maybe.
3) Back to the 2 album a year format
They would've done solo projects, they were already doing solo projects in the late 60s and playing on other sessions. Most of the first solo albums were leftovers from Get Back, Abbey Road, and White Album sessions.
4) Back to doing world tours
John was doing just charity shows. I think they may have done "under an assumed name" projects, all of them had uncredited appearances on many albums in the late 60s-early 70s.
5) John Lennon still alive today
We forget about the car crash he was in in the late 60s. Lost Weekend may have come sooner, and he may have never kicked heroin had he not left them.
George seemed like the only one who was definite about not wanting a Beatles reunion. John and Paul may have wound up writing together again, that part I do think would've happened. John was the leader of The Beatles from the beginning so that's why the other 3 never did it.
The breakup would've happened in 1973 if you based it on riding out the contract.