We've made leaps and bounds towards genetic manipulation lately and are now able to artificially create things such as ribosomes. What that effectively allows us to do is create bacterias that eat one thing as a fuel and create whatever we want them too. This has serious potential to end our oil problems for good.

Besides that, there are plant based oils that can be used for plastics, again though, the industry will have to grow up around the demand for it, we won't see it happen until there's a need.

The capitalist/commercial nature of our society allows us to progress at extremely fast rates but the downside is that unless there is money to be made things don't happen. To go a little off topic, it's the reason why space colonisation is just a pipe dream without some incredible scientific breakthrough, unless there's profit to be made it'll never happen. The best chance it has is if it turns out mining could turn profits, it's unlikely to happen though.

I just don't really see the human race dying out because of a resources issue. Alternatives will be found and if they can't be then life will change, something like that won't ever kill us though, we're far too adaptable.