Originally Posted by Beerstalker
I could have sworn that I saw Nathan Stark talking about timelines in one of the previews for what's coming up in this season of Eureka. That leads me to believe they will end up trying to go back to a different timeline at some point. However, I don't know if they will ever go back to the original one before Henry messed stuff up since it really seems like they have forgotten about that timeline. After all Henry is the only one that should still know about it, and now he seems to be all about Grace and doesn't seem to ever mention Kim. Although I guess that might be a good reason for him to go back now that he is over Kim, he can look for Grace in the original timeline.
I saw that preview too... and it fed into my speculation/guesswork.
Originally back in the first time-alteration... only Henry and Jack remembered the alternate future... but Jack was mindwiped by Henry so he wouldn't pine over the lost future. Now that Jack is with Alison anyway, it would be ok for Jack to remember that alternate future again.
It has always been left nebulous as to whether Henry just let go of that future OR if he mindwiped himself at some point. I used to look for signs that Henry remembered... but haven't seen any in a while.
To be fair, though... they did fix that time-travel episode in the end. Henry from the future had gone back and saved Kim... thus creating the alternate future... this alternate future then was fixed when Jack went back and stopped Henry... though Jack and Henry then had memories of both timelines... but the original one had been restored by story's end in that case.