I think that we will always find a way to survive. Regardless of the natural resources, scientists are getting better and better at finding alternative ways to exist without complete dependence upon the natural resources.
Hopefully, as stolperia points out, conservation will become more widespread and we will never reach "critical mass."
I think the development of substitutes for diminishing natural resources will continue and become more important, with businesses and governments being forced to provide more funding for research and development. I hope that conservation of natural resources will become more widespread so that we won't reach crisis point before alternatives are available in the case of critical resources.
Unfortunately, implementing new technologies is a slow process. I think there will come a day when many of our natural resources are gone but we still have not implemented the use of alternatives. With that said, technology changes and grows at an alarmingly fast rate. For example, we can now print solar panels in inexpensive sheets; the same panels would have cost exponentially more just a few years ago. If we can speed up the process of switching to renewable resources, we may have a chance to avoid some of the catastrophic consequences that would result from a lack of natural resources we currently use. The technology is there. It's just the implementation that is going to be an issue.
I wish I could be optimistic about future scenarios for the earth. Whilst I do desperately hope that alternatives to non-renewable sources of energy can be found and developed, as #5 states, I don't really see that countries are seriously investing much time, energy and resources into the search for renewable energy. I think we are going to see some kind of disaster but maybe in a more limited fashion and maybe in countries that are less developed in the first place.
It's not going to happen anytime in the near future. We are not going to run out of the natural resources that we really need (like food) because they are renewable. We will someday run out of oil, but by then we'll have figured out alternatives. I don't think that something Malthusian like #4 is suggesting is very likely to happen.
Natural resources and humanity are a balance. When we overpopulate and use up most of everything, humanity will suffer some sort of catastrophic mass failure (which can be as slow and subtle as just starving) and the population will be drastically reduced, allowing nature to regrow and replenish.
I foresee a day when future generations will be mining today's landfills and dumps to recover the resources that we are wasting today. I do agree with #2, it is, and will continue to be, a process driven by economic pressures. Right now it may not be worth breaking down small items to reclaim metals that are still relatively cheap, but as the easy-to-extract minerals are taken up, and the cost of energy continues to rise, there will come a day when it will be worth everyone's time to recycle more completely.
A number of countries -Sweden comes to mind- have been working to build recycling right into products from the outset. I think we will have to think this way more in the future. I also think that we may see a return to the days of keeping items longer. Forty years ago, small appliances like toasters were very expensive to buy, and when one stopped working it was sent to a repairman. Now they are so inexpensive that people just toss them and replace them. I suspect at some point that will come full circle.
AGREE WITH #2
BUT I THINK HUMAN WILL EXTINCT BEFORE THE NATURAL RESOURSES RAN OUT