BTW, I will not be sad at all to see Rebels go the way of the dodo. In fact, hopefully, we will have all forgotten about it entirely over the course of the next few years.
...and perhaps Filoni and company will soon be granted permission to cover the ground between RotJ and TFA, which would allow for plenty of (perfectly acceptable to us old-school fans) Jedi action, freaky lightsaber designs, and ridiculously overpowered starships.
Why? There can be plenty of acceptable jedi action and freaky lightsaber designs in Rebels too. And it's actually far more belivable to be beacuse the Jedi order is dead for less than 20 years, sop lenty of time for a decent number of survivors to show up, while in FA there have been no Jedi at all for 30 years straight since Luke failed at training a new generations, and the old survivors probably died of old age or are too old for that s**t (to quote Lethal Weapon).
As for ridiculously overpowered starships, that's the bread and butter of Empire shipbuilding.....they invented the Death Star after all.
So Rebels is in a far better position to show jedi action that FA, which will have to do with Luke and whoever might live through the rebellion (Ashoka will be a bit too old, Yoda and Obi-Wan are dead, Rham Kota Quinlan Voss and any other legend survivors are getting too old as well); only Kanan and Ezra will have the right age to be properly active.
The FA timeline is actually much better suited to a "rogue squadron" style series than one showing any Jedi.
As for Rebels life expectancy, we all knew that since it's set 5 years before ANH there can be only about 4 seasons before the movie takes over.
Well, they managed to drag The Clone Wars out for five seasons in spite of the war only lasting three years in terms of the established timeline, so it is possible that Rebels could run more than 3 seasons if Disney thinks there's a market for the show.