This photo has a lot of potential, but we're talking many days work. Main difficulty is that because of your high vantage point, we can't feel the sense of depth. We can tell, in other words, is how far (or how close), the different parts of the landscape are to them. Feeling how far things are—how far they are looking—is, in my mind, essential to the feeling of isolation you want to convey.
The project, therefore, would be to see if it's possible to somehow give this a sense of depth. No one magic tric. I would work on this in stage. First would be to isolate and separate the different major pieces of the landscape. For that, I would follow both their gaze and what seems like a natural design that moves from center to right.
I would experiment to find the general printing time for each that would give me a sense of depth and distance.
Next step would be to localise different larger elements. Most important one, as Patrick Robert James pointed out, is the promontory on which they are sitting. It needs to be separated from the landscape in order to show they are sitting atop of it. I would also work at that point on the trees (right) and the darker line in the back. The trees on the right are especially important since they are the only objects that give a sense of scale. In order to see how far they are, they need to look like trees, not like bushes.
Next step would be to work on local contrast. That's the point at which I would (or might) use a different grade. That part is probably the longest. I've outlined some parts I would probably work on, but I might throw out the results and try different parts. The difficulty would be, if I were indeed able to figure out the depth problem, to harmonize the smaller parts with the whole.
That small piece of landscape in front on the trees I mentioned before is also important. That, as well as the trees, is what they seem to be looking at. I say "seem" because that's what's interesting about this picture. The ambiguity as to their relationship with the landscape. Impossible to tell if they are talking to each other (therefore not involved with the landscape), it the man on the left is talking while the other is listening, if they are both lost in thought, if they are both contemplating something specific about the landscape on the right, etc...
It's a good photo, but it's a though negative.