Consider an analogy to the cells in our own bodies. Cells can divide (with some exceptions), yet the cells in our bodies do not keep dividing till they run into local resource limits, the equivalent of subsistence limits. There are signalling systems that tell healthy cells when they are "supposed" to stop dividing, and these mostly work. The analog to saying that people will evolve to get around obstacles that stop them from breeding is that cells will mutate till they are dominated by cancer cells. That isn't the whole story. Our immune system kills off most of the malignant cells we produce - we have social systems at various levels which could do the equivalent. If we (as a global society - a kind of weak singleton) can add layers of control faster than breeding mutations pile up, we may be able to contain runaway breeding indefinitely.