How large is large? Well, from the get-go, the article asks you to think about energy in units of PJ (Petajoules, 1015 joules), and EJ (Exajoules, 1018 joules). The fact that these prefixes need to be explained because they are used so seldom indirectly indicates the magnitude of the problem. Also eye opening one of the equivalences they provide: a million tonnes of oil equivalent (Mtoe) is 41.9 PJ. The total primary energy supply last year was 514 EJ, so you can do the math. Simply put, we use tremendous amounts of oil, and while it will eventually run out, we'll be seeing plenty more of it the rest of our lives.
If you don't agree with that last statement, then read the rest of the article. The authors spend most of the article looking at the alternatives being used and proposed. None of them will come close to replacing what is needed. We can't grow our way out of this, or use bugs or algae on a large enough scale. The summary of the article is pretty clear cut and impossible to argue with:
"Transport fuels of the future will require numerous sources; there is no silver bullet."
[*] I'd also add political commentators and talk-show hosts, but does anybody here think it would do any good? People like that already know the answer; what's the question?