There is huge significance in this line uttered by Juliet in her final moments.
I believe that it is beyond doubt that Juliet's consciousness is drifting between two timelines. Just as we have seen happen to Desmond, Minkowski, and Charlotte, her mind is quickly switching between two timelines. I believe the timeline she is drifting to is the Alternate Reality, in which 815 didn't crash. So let's look at the evidence. And just to clarify, I am aware I am not the first one to propose this theory, but I would like to first look at some evidence before taking the theory slightly further....
Firstly, Juliet says to Sawyer "We should get coffee some time". She seems confused, and doesn't make sense. This is similar to when Faraday is holding a dying Charlotte in his arms, and Charlotte is talking nonsense. Charlotte says "Turn it up - I love Geronimo Jackson". Just like Juliet, she is talking out loud about another reality. Ironically, both women utter these confused words whilst dying in the arms of a man who loves them, whilst drifting between two times.
Secondly, there is the crying. At first, we don't hear Juliet's cries. Then Kate hears them, and the cries continue for a minute or so. Then the cries subside again, and we have silence. Juliet appears to be "blacking out" When your consciousness is in one reality, the body in the other reality blacks out, consistent with being temporally displaced.
Thirdly, there is the fact that Juliet wanted to tell Sawyer something. Miles states that Juliet wanted to say "it worked" The "it" would be Juliets referencing of the plot to change time. Juliet is dying yet is trying to tell Sawyer that "it worked". She knows this because she is drifting between both realities.
To me, these three things not only prove that Juliet is drifting between two times, but that she is definitely drifting between 2007 on island, and a reality she knows is the AR. To say the words "it worked" she simply must know it is the AR.
But here's the interesting thing: I propose that eventually, all our characters consciousness's will start drifting between the two timelines we see. There has to be some kind of device to make both realities relevant to Lost's overall plot, and this would be it. Jack, Sawyer, Kate and company start having these lapses of consciousness, where they realise that in some sense, Jughead did work, and that they are drifting between two times.
To further back this up, just look at the way our Losties interact in the AR. Many people have speculated and theorised that they perhaps know eachother, or remember something in a slight manner. For some reason, they are drawn into talking with eachother. Jack has an enquiring look on his face at all times. It is not a look that suggests he knows everything, but it is a look that suggests he thinks he knows something. He feels something is familiar about these people but he can't quite put his finger on it yet, so he says nothing and get's off the flight.
Also, let's a have a good hard think about Desmond for a moment. I am aware the following is speculative, however it is very thought-provoking. Firstly, let's take the popular theory that the round the world boat race was actually set up by Widmore and Eloise in order to help events along and make Desmond crash on the Island. However, this is an AR in which the Island is gone, underwater. If the Island is gone, Widmore wouldnt need to manipulate Desmond into the race. Furthermore, this means that in this AR, Desmond would have no motivation to be training for the race, and would not have met Jack running the steps in the stadium. All of this means that in this AR, Desmond has probably not met Jack. So then, let's ask ourselves, why on the plane does Jack seem to recognise Desmond? Is it because he ran the Tour de stade with him? I seriously doubt it. I think deep in Jacks consciousness, a part of him remembers events on the island, and seeing Desmonds face triggers this.
Now if all this is true, and our characters consciousness start to travel back and forth between realities, doesnt this mean death for them all? Well no, I believe The island/the universe has a plan for them all. Charlotte died because she couldn't find a constant. But they are all eachothers constant. They are all together in 2007, and we can see that in the AR in 2004, their lives have once again started to become entwined. Some form of course correction is making sure that their lives start to intersect again. And their lives have to intersect if they are to become eachothers constant, and not perish.
To sum up, I think it is inevitable that Jacks consciousness, and some, if not all of our Losties consciousness's will start to travel back and forth between our two realities. This is how the two realities will meet in the middle, and why both realities will be of importance.