I've been thinking s lot about the motivations of creating the first film. In hindsight, bringing JJ on was because they wanted a soft reboot sequel. They wanted Star Trek 09. There's nothing wrong with that but it's interesting to note the big shot and the ripples that follow.
I imagine the entire script started with a simple question.
What if Leia had made it to ObiWan?
So in OT speak a very similar setup would have happened. Stormtroopers Attack Obi Wans house, Vader lands and has his battle at the beginning, and R2D2/C3PO are programmed with the coordinates to Yoda, given Luke's Lightsaber, and sent to his farm. Luke takes the droids into town to wipe their memory, gets tangled up with Han saving his life, Han takes Luke home, Skeleton Relatives, Luke convinces Han to take him to Yoda, Yoda trains, Yoda feels destruction of Alderan and sends Luke to Yarvin 4 to warn the rebels. 2 fold death star infiltration and destruction culminating with a semi trained Luke fighting Vader.
I like the idea that history repeats. Luke failed, so someone just to try. Trust in the wisdom of Space Magic.