There are other ways of disposing of a body. Im an organ doner, so they can take what they want and give the rest to science. At least then it may be somewhat useful. Cremation has been slowly becoming more popular over the last 20-25 years. Thats an easy option to solve the problem.
Space for burying was bound to run out eventually. Its not such a bad thing. Given the stuff embalmers put in the bodies its probably best that they dont wind up in the ground. Most of my family plans on going that route.
There's also the option of doing what they did in Paris when the city expanded over a cemetary. Exhume the bodies and stack the bones in catacombs. I imagine that wouldn't be too popular though as it would mean screwing with other people's graves.
I did the same thing years ago. They can take what they want burn the rest and spread the ashes over Johstone Straight.