Oil is harder and harder to find every year (we already took the easy stuff, nobody finds super-giant fields anymore)
The stuff that was "the easy stuff" forty years ago and the stuff that is "the easy stuff" today are very different things. It is normal that, upon decrease in supply, research is invested into increasing the economically-effective supply. That's how we got steam-injection and CO2-injection into oil-wells, which is why the US still supplies 2/3rds of its own oil resources (as of 2007, at least), despite Hubbards Peak pegging our peak production in the early 1970's.
All the alternatives that were supposed to fill the gap are failing to deliver
Of course they are. Because they were all pipe-dreams. In the meantime we've had a viable 'alternative' -- such that at least one industrialized nation (South Africa) has been relying upon it for years: the Fischer-Tropsch process. It generates liquid hydrocarbons from coal at a rate which is economically feasible with sustained non-futures prices of oil at over ~$80/barrel, with coal at ~$20/ton. (Please note: this simply has not happened yet.)
Even oil that's harder to get (e.g. in deep water) doesn't help much as it is generally produced at a slow rate
Projection fallacy. As I mentioned above; the "harder to get" only stays "harder to get" until it becomes "easier to get". The fallacy here is in thinking that this is a fixed term rather than malleable based on technical prowess. I again mention steam-injection and the fact that it revitalized the Californian oil industry from essentially total death to viability.
The average person is mystified as the price of everything seems to rise at once
This is a "and then magic happens" statement. Please don't take past fears regarding food availability as viable indicators of the future. We already grow far more than enough food to feed the entire world... and there are plenty of techniques available to increase agricultural output that we just haven't implemented very much yet. Everything from genetically-engineered nitrogen-fixing plants/bacteria to terra preta.
Business and whole national economies are squeezed by rising prices
Increased prices result in increased ingenuity for discovering alternative means to the same ends. Fundamentally the 'function' of technology can be said to be the increase in the fungibility of a given resource. Back in the day we used whale blubber for a broad array of things. When the whales started getting scarce, we switched to coal and coal-gas. Then we switched to oil because it was a better hydrocarbon and we could get at it cheaply. (Though really, we still use coal for MOST of our energy needs. And the stuff we use oil for we could substitute coal for. Or even charred woody-plants 'torrefied lignocellulosic stocks' grown in agriculture.)
One thing I've noticed a lot is reports about "Oil Sands", "Oil Shale", "Vast new possibilities of X barrels from biodiesel/microbes/algae/thermal depolymerization" etc. and none of these reports ever mention the rate of production that is expected (and years later they seem to have delivered nothing).
"seem" is the key term here. North Dakota is enjoying an oil-boom due to active extraction of shale-oil. Biodiesel in its various forms is not a viable hydrocarbon resource today, although there is at least one commercial plant selling to the US Military (at absurd costs.)
Civilization runs on the constant supply of power. If that power declines 5% every year we are back to the middle ages before very long, and it's hard to develop a Friendly AI on an abacus.
If, sure. But it's just not going to happen.
the Fischer-Tropsch process. It generates liquid hydrocarbons from coal at a rate which is economically feasible with sustained non-futures prices of oil at over ~$80/barrel, with coal at ~$20/ton.
Where do you get those numbers?
Traditional plants are 10% efficient. The Chinese plant is 20% efficient. The numbers I've seen suggest that the operating costs aren't much more than materials. A ton is about 6 barrels, so if coal/ton is about the same as oil/barrel, the Chinese plant is profitable. Indeed, those prices have been the same for the past ten year...
To me the following points seem hard to argue against: