eeh. We will adapt as with the oil price drop, or market will crash and it’ll be the zombie apocalypse without the zombies undead. (Undoubtedly large numbers of living zombies will roam if it goes that far) Or, the Earth will go through another cycle and we will all be bathed in radioactive oil rain. Since the universe loves irony I am going to assume that we run out of oil, do a big time conversion, and people everywhere beg for more oil, then oil rain comes. That or, the “deadline” of how long oil is ganna last keeps getting pushed further and further back as more deposits are found where noone would have thought they would be.
About deposits:
The reason for the deadline being pushed back is that the deadline is based only on KNOWN (and not estimated or calculated) deposits.
But new deposits are once in a while found as you mention.
Search for new deposits is much more intense when the oil price rises.
The oil price rises when the current deposits start getting drained.
So: it is a little game where the oil price stays within a pricerange, while the deposits change. That’s how the industry remains profitable (super profitable afaik).
Now, there certainly is a finite number of deposits, but we are not close to finding most them, let alone depleting them yet. Schistolithic oil is an a example of the whole thing.
About alt fuels and energy sources:
The rage about alternative fuels is mostly EU driven (ok Brasil and China who lack oil are also pushing for alt sources, while the US invests too so that they will not get outteched) and this is because Europe nowadays has a major energy deficit. (ok there IS some oil in the Eastern med, just starting to get extracted, but other oil deposits and most coal deposits are getting exhausted round here)
So yes, we need alternative fuels (and energy sources)
Now biodiesel is the equivalent to diesel and ethanol is equivalent to gasoline.
These are (for now) more expensive to make than oil. Micro-algae might be a solution though.
These are organic in nature and bacteria can live off them (but not inside extracted oil). So they can go bad much more easily.
These have lower calorific values per weight (and volume) so you need more of them for the same distance. They are less efficient.
They are better for the engines though, they got higher Octane/Cetane numbers and help with lubrication too.
(but they act as solvents to rubber, hence the need for specialized flex-engines for 100% biofuel use)
Besides, nowadays an effort is starting with companies using cheap solar (and wind) electricity to create standard hydrocarbon fuels by breaking CO2 and H2O and combining H and C in proper ratios for the fuel desired. It will be inefficent for as long as solars stay expensive. After that it might go up.
The fact is though, that no known alt fuel has better efficiency per volume than oil products. (except nuclears and rocket fuels that are inconvenient)
Not Hydrogen (too hard to compress & contain), not biofuels, not electricity, not compressed air, not sunlight… etc.
So, it is certain that in the near future there will be some effort to use alternative fuels, but the oil industry will not change for a long time.
In cata terms, i would not think that anything needs to change WRT fuels. As already assumed, i would expect that gasoline stations will still exist and that all engines are flex and we do not need to distinguish between eth-gasoline and biodiesel-diesel. (waving their differences off to avoid overcomplicating the game)