Desolation and Dislocation

Having an elaborate and well-thought-out idea is all well and good, but when the do-ability is questioned you are faced with two choices:

1) Work like hell and organize every aspect of your film down to the last spec of dust.

2) Come up with an alternative idea that's more do-able, that still holds your enthusiasm and artistic vision.

An idea that I've been throwing around in my head is the story of two people trying to survive in a desolate and dangerous post-apocalyptic landscape. It has the potential to be very cinematic and moving, Zombies is something that can be overdone but I feel that with the recent popularity of these flesh-eating creatures I would be playing to a lot of people's interests.
Recently there was a video game released, 'The Last of Us' and follows the story of a man and a young girl as they try to survive in a dangerous world ravaged by a deadly virus. What strikes me about the game is that the real threat to our characters isn't the zombies that have almost wiped out humanity, but it's the humans that are left that pose the real danger. It basically shows us that people change and become extremely self-reliant when given the will to survive.
In the game, the relationship between the two lead characters (Joel and Ellie) is vital to the emotional impact of the story. This is something I need to seriously consider with my two characters. They learn from each other, they rely on each other and it is clear that they genuinely care for each other.

I can't imagine location will be too problematic, I have a lot of areas in mind that give off a desolate and post-apocalyptic vibe, particularly in the rural areas near me e.g. the Purdysburn hospital complex. The cast is very small, two people at the most and (if I decide on the zombies) a cast of extras. A lot of fun can be had with costume and makeup and with the resources available to me this idea seems very do-able.