I had an impression that they will try to change the future but they will only see the things would just happen whatever they do, like in Deja Vu. However, the story is very open to change easily and writers love to surprise viewers. I think we must not be able to see if the future is changeable till the end of the show.
For our world, I believe that we can change our future. Our fate is there but there is allways something to do about it. Diversifying the fate is the fate too.