Once in a lifetime

Or rather seven ... :)

Jedi might have found the path to immortality.
Does that mean the Force will be shaken to its very foundations, unbalanced to the point that another Dark swing is needed to preserve the universe's entropy ?

There are so little Jedi remaining after ROTS: Yoda, Obi-Wan, Anakin in a way, and the now few castaway Jedis that will surely be swept away by an anger filled Vader.
So the Force is clearly unbalanced at the beginning of ANH, and will remain so until ROTJ.

But what of the following years ? According to the expanded universe (EU) novels, the Jedi are to rise again thanks to Luke's academy. I am still not totally sure if EU novels are considered canon, but since no other movie or TV show is supposed to cover that time span, we can only but try to guess.

And so, it is inevitable that the Dark side came back after the glorious days of the new republic's victory over the Empire.
Be it by political or direct Force corruption, I feel the universe needs alternate positions to fuel itself.

After all, don't the prophecy and the whole movies gravitate around the "balance" concept ?
Theoretically, a balance is a stable but easily modified state of contradicory powers within a system (the universe, or a marble on top of an inflated balloon).
A small amount of energy or Force nudge is all it takes to have the marble slide one way or the other, to make the universe hurl towards the Dark or Light side ...

But maybe another balance can be reached, maybe that inflated balloon is more like an air mattress, with several possible balance spots ?