I think there is huge scope for optimism provided people act soon.
As I said before, many of these problems can be delayed indefinitely by the increased usage of already available technologies. IMHO, hybrids offer the best hope in the short to medium term.
In 2000, 54% of petroleum in the US was used by all forms of road transport. At current usage rates that accounts for around 10-12 million bpd. Other countries would have similiar usage rates.
The average US car gets around 20 mpg. Developments in hybrids using lithium ion batteries are verging on the profound and easily have the potential to make 100 mpg engines on a car with a 300 mile range. That car can then be recharged relatively quickly via a standard AC outlet.
This technology is available NOW without the huge infrastructure costs and complexity of a hydrogen economy. All that is required to make it so, is the political will.
Once you get cars weaned off petroleum then most of the problems, whilst not solved, get relegated to the 22nd century. Hybrids will only get better as more R&D is put into them.
In short, provided good sense prevails (and that is the big IF) then there is no reason to panic. (Although a couple of acres in the country would be nice...)