Surprisingly Eddie Thawne killed himself in order to prevent reverse flash(Eobard Thawne), from coming into existence.
This created a black whole in the existing reality that threatened to destroy the entire world. We see flash running directly into it in order to reverse the damage.
I speculate that season 2 will be an alternate version of season 1, since the black hole basically altered reality.
We will see reverse flash again, albeit in some other shape or form, where he is not conscious of the alterations to the timeline. It has already been shown that even with his knowledge of the speed force and time travel, he is still susceptible to time alterations from time travel done by other people who have access to the speed force.
We have seen that when one disaster is avoided with the aid of time travel, that another is created. This means that this major alteration in the timeline following the black hole will create something entirely different.
There are two ways the writers can go with this. They can redo season 1 with some twists and new bad guys, or they can create a new reality altogether. They can even follow the comic more closely, since all the deviations can be explained away by this cataclysmic event.
Being that they plan on introducing wally west(The second flash), and cobalt blue, there are so many clever things that the writers can implement, since we have a storyline that takes place both in the past and present, creating a timeless universe.
Flash is genius.