This is all very complex for those of who just watch the films, I prefer
1) Luke is the last/first Jedi
2) The rest of these people I've never heard of are shot in the face with a space-uzi before A new Hope.
That will be entirely up to the writers at this point. They might cancel Rebels after two seasons and repurpose them for a post-New Hope cartoon, or even a post-Return of the Jedi cartoon (lots of time to play around there) with the same characters. Then again they might keep Rebels going for four or five seasons until the characters would get to the point of A New Hope.
They might start up a completely different story around the time of The Force Awakens, once there is a story for people to see this December.